DiFA Projects available for PhD cycle 41

Project code Main supervisor Title of the project

1 Brusa1 Brusa Exploring the nature and feedback of low-power radio AGN in the SKAO era
2 Brusa2 Brusa New populations of Supermassive Black Holes in the Deep Universe
3 Cadelano1 Cadelano Constraining the primordial properties of dense stellar systems
4 Ciotti1 Ciotti Dynamics of elliptical galaxies
5 Despali1 Despali What alternative dark matter models do to galaxies: studying galaxy
formation in the AIDA-TNG simulations
6 Despali2 Despali A SHARP view of dark matter in the Euclid era
7 Ferraro1 Ferraro Searching for Fossil Fragments of the Galactic bulge formation process
8 Ferraro2 Ferraro Playing with the physics of Blue Stragglers
9 Ferraro3 Ferraro Probing the early history of the Milky Way formation with the chemical DNA
of Bulge stellar systems
10 Ferraro4 Ferraro Unveiling the physics of Globular cluster cores
11 Gitti1 Gitti AGN feeding-feedback cycle in cool core clusters with Hα nebulae
12 Gitti2 Gitti Radio and X-ray connections in cool core galaxy clusters
13 Lardo1 Lardo Leveraging Machine Learning to Decode Multiple Populations in
Stellar Clusters
14 Lardo2 Lardo Decoding Multiple Populations - Bridging Star Formation Insights
Across Galactic Environments
15 Marchesi1 Marchesi Searching for high redshift AGN with current and future X-ray
and radio facilities
16 Marchesi2 Marchesi Characterizing the emission mechanisms of extreme high synchrotron peak
blazars: towards a new population of CTAO extragalactic emitters
17 Marinacci1 Marinacci The effects of baryonic physics implementation in simulations of galaxy
formation and evolution using Lagrangian and mesh-based hydrodynamic
codes
18 Marinacci2 Marinacci Forecasting the gravitational wave signal in cosmological simulations
for current and upcoming cosmological surveys
19 Marulli1 Marulli Exploring Gravity Models with gravitational redshifts in galaxy cluster
environments
20 Marulli2 Marulli Cosmology with Bayesian deep neural networks to learn the properties of
the Cosmic Web
21 Marulli3 Marulli Cosmological exploitation of the statistical properties of Cosmic Voids
22 Metcalf1 Metcalf The Properties of Strong Gravitational Lenses
23 Miglio1 Miglio, Straniero Stars as laboratories for testing fundamental physics
24 Moresco1 Moresco Exploiting Gravitational Waves as cosmological probes in view of the new
upcoming large GW and galaxy surveys
25 Moresco2 Moresco Towards a comprehensive clustering analysis: maximizing the scientific
return through the combination of lower-order and higher-order correlation
functions in configuration and Fourier space
26 Moscardini1 Moscardini A multi-wavelength view of galaxy clusters from Euclid and XMM-Newton
27 Moscardini2 Moscardini Detecting Clusters and Voids using Weak Gravitational Lensing
28 Moscardini3 Moscardini Statistical Tools for Cluster Cosmology Studies in the ESA-Euclid Era
Mission
29 Mucciarelli1 Mucciarelli Implementing new physics in the modeling of the stellar atmospheres
30 Mucciarelli2 Mucciarelli Evolution of CNOPS elements in the Milky Way
31 Mucciarelli3 Mucciarelli Reconstructing the mass assembly history of the Milky Way
32 Mucciarelli4 Mucciarelli Chemical characterization of the Local Group: identifying the chemical DNA
of Milky Way satellite galaxies
33 Nipoti1 Nipoti Local gravitational instability of stratified rotating fluids
34 Nipoti2 Nipoti Simulations of the collisional evolution of globular clusters with Monte Carlo
methods
35 Nipoti3 Nipoti Global stability of stellar discs with dark matter halos
36 Nipoti4 Nipoti Probing black holes through gravitational wave and quantum
signatures
37 Nipoti5 Nipoti Hydrodynamic simulations of Terzan 5 and bulge fossil fragments
38 Pallanca1 Pallanca Exploring binary millisecond pulsars in globular clusters through optical/
near-infrared observations.
39 Roccatagliata1 Roccatagliata Formation and evolution of solar system analogs: gravitational
interaction with planets and/or external perturbers
40 Tailo1 Tailo Investigating stellar rotation in low and intermediate mass stars
41 Talia1 Talia Exploiting the Euclid Legacy for galaxy evolution with ELSA
42 Vazza1 Vazza Studying the magnetic connection between the cosmic
web and the primordial Universe
43 Vazza2 Vazza Unveiling the nature of dark matter from radio observations with SKA
precursors
44 Vignali1 Vignali Dual and binary super-massive black holes candidates in the
gravitational-wave era
45 Vignali3 Vignali The realm of the high-redshift Universe unveiled by JWST
46 Vignali2 Vignali Shedding light on the physics of the most massive, highly accreting SMBHs
at high redshift through a multi-wavelength study
47 Vignali4 Vignali AGN physics and demography in the XMM-Newton-Euclid Fornax
Deep Field

1
 PhD project in ASTROPHYSICS

Title of the Project:

Exploring the nature and feedback of low-power radio AGN in the SKAO era

Supervisor: Marcella Brusa (DIFA)

Co-Supervisors: Marisa Brienza (INAF-IRA)

Scientific Case:
Supermassive black holes at the center of galaxies recurrently accrete gas from their
surrounding environment, giving rise to some of the most powerful phenomena in the
Universe, visible across the entire electromagnetic spectrum. While it has become clear in
recent decades that the energy released by these so-called Active Galactic Nuclei has a
considerable impact on the evolution of both galaxies and their surrounding environment —
thus becoming a key element in galaxy evolution models— many details of this phenomenon
are still not fully understood.
In particular, mostly due to observational limitations, the study of AGN in the radio band has
been restricted for many decades to powerful jetted sources extending over scales of hundreds
of kiloparsecs. These are typically associated with the most massive galaxies in the Universe
and clearly contribute to maintaining their star formation quenched. However, more recently,
with the advent of more sensitive and high-resolution radio surveys, it has become clear that
these sources represent only the tip of the iceberg. AGN radio outflows on kpc scales, in the
form of both winds and jets, are indeed a much more ubiquitous phenomenon in all kinds of
galaxies and thus can potentially have a more widespread impact on galaxy evolution.
Observations suggest indeed that despite their low power these outflows are able to promote
turbulence in the interstellar medium, as well as compress, redistribute, and even expel the
gas from the host galaxy, affecting its star formation history. However, a clear characterization
of the properties of these radio outflows, including e.g. the occurrence and origin of jets vs
winds, of the relationship with the multi-band counterparts (atomic, molecular, ionized, X-
ray gas outflows), and of the connection with the overall properties of the host galaxy and
environment is still to be achieved, from the local Universe to the Cosmic Noon.
Outline of the Project:
The main goal of the proposed PhD project is to address the aforementioned opened questions
by exploiting new-generation radio data from SKAO precursors and pathfinders (including
JVLA, LOFAR, MeerKAT, VLBI), in combination with multi-wavelength data in the X-ray,
IR, optical and mm bands. In particular, the PhD candidate will focus on:
• detailed multi-band investigations of a few archetypical low-power radio AGN to
understand the origin of their radio emission (jets vs winds), the connection between
the radio outflows and nuclear Ultra-Fast Outflows (e.g. XMM-Newton) and the
physics of their interaction with the surrounding interstellar medium (e.g. ALMA,
JWST).
• statistical analysis of new samples of low-power radio AGN selected by cross-
matching X-ray (e.g. eROSITA) and optical/NIR (e.g. Euclid) surveys with radio
surveys.

Fig. 1. Example of a powerful quasar with low-power jets (detected by the VLA, white colors
on the left), which are interacting with the interstellar medium as probed by JWST (OIII
emission in colors) and ALMA (cyan and magenta contours on the right) from Cresci et al.
2023. The PhD candidate will have at their disposal similar or higher resolution data.

Overall, the PhD candidate will be trained in AGN physics, in handling interferometric data
and multi-band data catalogs, and in analyzing and interpreting AGN data from different
instruments. She/he will also acquire scientific independence by, e.g., writing observing
proposals and presenting the results of the work at international conferences. The PhD
candidate will join the AGN group at DIFA and INAF-IRA and will have the opportunity to
visit renowned research Institutes and Universities abroad through our collaboration
network. Generous research funds are available for the entire PhD program.

Contacts: marcella.brusa3@unibo.it (office 4S6), marisa.brienza@inaf.it

 PhD project in ASTROPHYSICS

Title of the Project:

New populations of Supermassive Black Holes in the Deep Universe

Supervisor: Marcella Brusa (DIFA)

Co-Supervisors: Marco Mignoli, Roberto Gilli (INAF-OAS)

Scientific Case:
Super massive black holes (SMBHs) at galaxies’ centers grow their mass by accreting
surrounding gas. During these transient phases, called Active Galactic Nuclei (AGN), part of
the gas gravitational energy is converted into radiation that our instruments can detect.
Observations at different wavelengths unambiguously indicate that SMBHs primarily grow
during hidden AGN phases, when circum-nuclear gas and dust absorb most of the emitted
radiation, and that the incidence of nuclear obscuration rapidly increases towards early cosmic
times (e.g. Vito et al. 2018). The reasons for this evolution in the obscuration are, however,
largely far from being understood. Very recently, the unparalleled capabilities of JWST have
in addition uncovered new, unexpected populations of growing SMBHs in the early
Universe, say z>4, whose observational properties remarkably differ from those of known
AGN at lower redshift pointing to a significant evolution in the physical properties of the
accreting and obscuring matter (e.g. Maiolino et al. 2025).

Understanding the reasons for the increase of nuclear obscuration with redshift and why the
new populations of high-z, JWST-detected AGN are so different from low-z AGN are the main
objectives of this PhD project.

Outline of the Project:

The proposed project will pursue the objectives above through a multi-band observational
approach. Our group is heavily involved in the major existing extragalactic surveys (CDFS
and COSMOS), and is leading a major effort in the J1030 field. The PhD candidate is
expected to search for and identify distant, obscured AGN in these fields by applying
known obscuration diagnostics and developing new ones based on data from the main
international facilities (see e.g. Mazzolari et al. 2024).

The combination of X-ray and radio data in the J1030 field (one of the deep at both
wavelength, see http://j1030-field.oas.inaf.it/ for a summary of the data) has allowed selection
of promising obscured AGN candidates that have been recently observed with ground- and
space-based spectroscopy by Gemini, LBT, VLT and JWST. The PhD candidate is
expected to reduce and analyze those spectra, measure the redshift, spectral properties and
obscuration level of the newly-discovered heavily obscured AGN, and derive their cosmic
evolution, probing in turn their contribution to the black hole accretion rate density in the
distant Universe.
In addition, the PhD candidate will exploit the available JWST spectroscopic and imaging
data to probe newly discovered AGN populations, such as X-ray silent broad line AGN and
Little Red Dots, to determine their physical properties and abundance, compare with those of
‘standard’ AGN, and reconstruct how the physics of accretion and nuclear obscuration
evolved with cosmic time.

The results from both components of the project will be used to constrain state-of-the-art
cosmological simulations of galaxy(AGN) formation and evolution, with a focus on the
characterisation of the black hole seeds population, and the role of obscuration and Super-
Eddington accretion for the growth of supermassive Black Holes in the very early Universe
(e.g. Pacucci et al. 2024).

The PhD candidate will be trained in AGN physics and demographics, in handling multi-band
data catalogs, and in analyzing and interpreting AGN data from different instruments (e.g.
JWST, VLT, LBT and Chandra). They will also acquire scientific independence by, e.g.,
writing observing proposals and presenting the results of the work at international
conferences. The PhD candidate will join the AGN surveys group at DIFA and INAF-OAS
and will have the opportunity to visit renown research Institutes and Universities abroad
through our collaboration network. Generous research funds are available for the entire PhD
program.

References: Maiolino et al. 2025 (A&A in press, arXiv:2405.00504), Mazzolari et al. 2024
(A&A 691, A45), Pacucci et al. 2024 (ApJ 976, 96), Vito et al. 2018 (MNRAS 473, 2378)

Contacts: marcella.brusa3@unibo.it(office4S6), marco.mignoli@inaf.it, roberto.gilli@inaf.it

 PhD project in ASTROPHYSICS

Title of the Project: Constraining the primordial properties of dense stellar systems

Supervisor: M. Cadelano (UniBo)

Co-Supervisors: E. Dalessandro (INAF-OAS), E. Vesperini (Indiana Univ.), J. J. Webb
(Toronto Univ.)

Scientific Case:

Star formation at any cosmic epoch is characterized by the presence of clustered systems such as
molecular clouds, massive young clusters, open clusters, and globular clusters. Establishing the
link between the origins and primordial properties of these systems is crucial to advancing our
understanding of star formation in the context of (1) galaxy evolution, (2) the physical processes
governing the formation and evolution of stars and star clusters, and (3) the role of dense stellar
systems in producing the gravitational wave events observed today. However, this connection
remains poorly understood.

Two key properties of star formation that any predictive theory must account for are the initial
distribution of stellar masses, i.e., the initial mass function (IMF), and the fraction of binary/triple
systems that form. The IMF is one of the most debated topics in astronomy, particularly regarding
whether it is universal or varies with the structural and chemical properties of the star-forming
environment. This distinction is critical, as the IMF influences most observable properties of
stellar systems, from star clusters to galaxies. Despite extensive efforts to study the IMF across
different environments, no consensus has been reached on its universality.

Similarly, stellar binarity is closely tied to the dynamical processes occurring during both star
formation and cluster evolution. It has long been recognized that binarity, and stellar multiplicity
in general, is a fundamental and inevitable outcome of any star-forming system. Understanding
the primordial binary population is essential for studying the formation and evolution of stellar
systems, as it governs key processes such as supernova rates, chemical enrichment, and stellar
dynamics. Moreover, continuous interactions between binaries and other stars are expected to
form hard binaries over time, enhancing the merger rate in these environments. These mergers
may hold the key to understanding the gravitational wave events detected by current
gravitational wave observatories, particularly in relation to the black hole mass distribution.

The goal of this PhD project is to constrain the primordial properties of dense stellar systems in
the Local Group by observing and modeling their present-day properties across different
environments. In particular, the project will focus on constraining both the IMF and the primordial
binary fraction, which will provide a significant leap forward in our understanding of the physics
of clustered star formation.

Outline of the Project:

Recent advancements in N-body and Monte Carlo simulations of star clusters, incorporating a
broad range of initial conditions (such as cluster mass, size, primordial binary fraction, black
hole retention fraction, and orbital properties), have shown that many present-day cluster
properties can be linked to their primordial characteristics. For instance, measurements of
radial variations in the present-day mass function serve as a powerful tool for constraining the
IMF of dense stellar systems. Similarly, the binary fraction measured across the entire cluster
provides a proxy for its primordial value and helps assess the role of the environment in
determining how many binaries form, survive, and eventually merge over the cluster’s long-
term evolution. The synergy between these state-of-the-art simulations and observational data
is opening a new window into our understanding of star formation in clusters.

Within this framework, our group has already been awarded more than 150 hours of observing
time on different stellar systems using the most advanced ground-based (ESO) and space-based
(HST, JWST) facilities.

During the first year, the candidate will learn to perform high-precision photometric analysis of
stellar systems. This will allow the characterization of the present-day distribution of stars
within clusters and their physical properties. In the second year, the candidate will spend a
research period abroad, likely in the US and/or Canada, working with leading experts in
dynamical modeling of star clusters through numerical simulations. These simulations,
combined with observational results, will provide the foundation for the main goal of the PhD
thesis: deriving the primordial properties of dense stellar systems. The third year will focus on
consolidating these results and synthesizing them into a comprehensive analysis of the early
conditions of clustered star formation environments.

Contacts:

Mario.cadelano@unibo.it
Emanuele.dalessandro@inaf.it
 PhD project in ASTROPHYSICS

Title of the Project: Dynamics of elliptical galaxies

Supervisors : Luca Ciotti – Silvia Pellegrini

Scientific Case: The internal dynamics of elliptical galaxies depends significantly on the
anisotropy of the velocity dispersion tensor. The effects of anisotropy are understood
quite well in the case of axisymmetric galaxies with a phase-space distribution function
depending on the two classical (isolating) integrals of motion, E, and Jz. Much less is
known about the case of three-integrals systems, even though observations suggest that
this may be the common case. The proposed thesis intends to systematize, clarify, and
extends the present knowledge of the field, by the construction of analytical and
numerical models of elliptical galaxies, to be confronted with the observational data.

Outline of the Project: Construction of oblate and prolate galaxy models, supported by
two and three integral phase-space distribution functions. Construction of the
kinematical (intrinsic and projected) fields, and comparison with observations to
constraint the amount and distribution of galactic orbital anisotropy.

Contacts: luca.ciotti@unibo.it, silvia.pellegrini@unibo.it

 PhD project in ASTROPHYSICS

Title of the Project: What alternative dark matter models do to galaxies: studying
galaxy formation in the AIDA-TNG simulations

Supervisor : Dr. Giulia Despali

Co-Supervisors : Prof. Lauro Moscardini

Contacts: giulia.despali@unibo.it

Scienti?ic Case: One of physics and astronomy's most pressing questions today is: “What is
dark matter?”. Astrophysical studies have shown that the standard cold dark matter model
(CDM) successfully reproduces observed structures in the Universe on large scales and the
CDM. Still, tensions with observations persist at the scales of galaxies and below. A solution
comes from alternative dark matter models (Warm or Self-interacting) that are able to
influence the dark matter distribution at the centre of galaxies and satellites. The next
generation of telescopes will bring exceptional progress in the observational domain,
providing a much larger sample of galaxies (Euclid, Rubin) and resolving scales down to
milli-arcseconds (ALMA, VLBI, ELT): it is thus the moment to take theoretical
predictions to the next level, by modelling the effects of baryons and alternative dark matter
at the same time.
The AIDA simulations are a new set of cosmological hydrodynamical simulations based on
different dark matter models, including a realistic recipe for galaxy formation: they are the
best simulations available to study the nature of dark matter from cosmological scales to

Figure 1. Outline of the new AIDA-TNG runs (Despali et. al 2025) that will be used during
this project.
dwarf galaxies. Thanks to the high resolution and complexity of the simulations, we will be
able to systematically compare the properties of structures, from clusters to dwarf galaxies,
and create mock observations in order to find estimators that can lead to new constraints and a
better understanding of the physics of structure formation.

Outline of the Project:

Warm dark matter influences the number of low-mass galaxies and satellites, while self-
interacting models modify the structural properties of dark matter haloes. This PhD project
involves both creating new simulations with such models and analysing the existing AIDA-
TNG runs, thus learning the fundamentals of computational astrophysics. Breaking the
conventional separation between theoretical and observational works, we will simultaneously
learn about dark matter and galaxy formation models. In particular:

- The first phase of the project will consist of an analysis of the cosmological runs,
identifying new statistical differences between CDM, WDM and SIDM. For example,
scaling relations of galaxies, the number count of haloes and subhaloes, the matter power
spectrum, and the evolution of the gas and stellar content of galaxies.
- In a second phase, the PhD student will then run additional boxes or identify systems to re-
simulate at higher resolution, to create zoomed versions of a few interesteing galaxies. This
will allow us to resolve the galaxy and dark matter structure with increased precision and
create realistic mock observations to be compared with real observational data from Euclid
and other telescopes (see Fig. 1 for examples of simulated observations).
- The results will be interpreted in the context of the current best data, such as the wide-field
survey that will be carried out by the Euclid telescope. In this way, we will derive new
constraints on the nature of dark matter.

The AIDA simulations have been developed in an international collaboration that includes
DIFA and INAF scientists in Bologna, together wit the IllustrisTNG group: Volker Springel,
Annalisa Pillepich, Dylan Nelson and Mark Vogelsberger. This will allow the PhD student to
interact with some of the most prominent researchers in the field of numerical simulations. In
addition, the student could be involved in the ESA Euclid consortium and the SHARP lensing
collaboration, focused on constraining dark matter with lensing. The collaborations mentioned
above will also provide the chance to spend a period of 3-6 months abroad.
 PhD project in ASTROPHYSICS

Title of the Project: A SHARP view of dark matter in the Euclid era

Supervisor : Dr. Giulia Despali

Co-Supervisors : Dr. Cristiana Spingola (IRA), Prof. Lauro Moscardini, Dr. Massimo
Meneghetti (INAF-OAS)

Contacts: giulia.despali@unibo.it

ScientiDic Case: In strong gravitational lensing, the image of a high-redshift source (e.g. a
galaxy or a quasar) is distorted and magniLied by the presence of an intervening object along
the line-of-sight that acts as a lens (see Figure 1). Lensing is thus one of the most promising
tools in dark matter studies: the distortion is due to gravity only, allowing one to directly
measure the total (luminous and dark) mass distribution of the lens. Besides the main lens,
strong lensing can detect low-mass satellites of the main galaxy. These are crucial tests of
alternative dark matter: (i) their number is the fundamental test of cold and warm dark
matter models; (ii) self-interacting dark matter can make low-mass structures very dense and
thus more easily detectable with lensing.
In galaxy-galaxy lensing, dark subhaloes are detected as localised perturbations to the surface
brightness distribution of magnified arcs. This method is, to this day, the only way to detect them
beyond the Local Group and has led to detections in HST, Keck and ALMA data. It is easy to
understand that the spatial resolution of the lensing images is crucial to detect small structures. This
way, we can reach smaller scales and detect perturbers down to M~107 M⦿. At the same time, we
need a larger sample of gravitational lenses as will be soon provided by the Euclid telescope,
launched in July 2023. Following predecessors such as SDSS and DES, the survey data promises to
greatly enhance our knowledge of the dark sector of the universe.
Outline of the Project: The SHARP collaboration and observing program has targeted 40 new
systems that have or will be observed soon with the Keck telescope: this is the only new optical
sample that targets lensed arcs beyond HST resolution. The current SHARP sample consists of data
from two observing runs with the adaptive optics system on Keck, including NIRC2 (H and K’
bands) and Osiris. Thus, this program will bring gravitational imaging to the same level of
constraints of MW-satellites and flux ratio anomalies and will make combined constraints stronger.
The PhD will combine on the analysis of lensing data from the SHARP sample and follow-up data,
with new observations coming from the Euclid mission. In practice:
- The PhD student will model the new SHARP lenses, reconstructing the mass and light
distribution of the lenses, arcs and sources using existing parallel codes. She/he will then search
for smaller satellites, which manifest themselves as surface brightness perturbations.

- We will use Euclid galaxies from DR1 and the following releases to constrain dark matter based
on their statistical and individual properties, such as total and stellar masses, half-light radii and
sizes, lensing Einstein rings and density slopes, satellite count or matter clustering. All these can
 be modified by warm and self-interacting models, which alter the distribution of matter inside
haloes, the depth of the potential well where the galaxies form, and the timescale of structure
formation or merging events. During the first analysis of the Euclid data, we have already found
hundreds of new systems which hold great promise for dark matter studies. The PhD student will
identify promising systems to analyse and propose follow-up observations.

Euclid new lenses

The SHARP collaboration and Euclid consortium framework will allow the PhD student to interact
with the gravitational lensing community. In particular, the SHARP data analysis will be carried out
in collaboration with the PI of the SHARP program Prof. Christopher Fassnacht (California UC
Davis), and international researchers in Germany and the Netherlands. These collaborations will
also provide the chance to spend a period of 3-6 months abroad, visiting partner institutes in
Germany or the USA.
 PhD project in ASTROPHYSICS
Title of the Project: Searching for Fossil Fragments of the Galactic bulge formation process

Supervisor: F.R. Ferraro Co-supervisors: B. Lanzoni, C. Pallanca Collaborators: E. Dalessandro

(INAF)

Scientific Case: The scenario of galaxy bulge formation is still largely debated in the literature.
Among the most credited models, the "merging picture" proposes that galaxy bulges form from the
merging of primordial sub-structures, either galaxies embedded in a dark matter halo, or massive
clumps generated by early disk fragmentation. Although the vast majority of the primordial fragments
should dissolve to form the bulge, it is possible that a few of them survived the total disruption and are
still present in the inner regions of the host galaxy, grossly appearing like massive globular clusters
(GCs). At odds with genuine GCs, however, these fossil relics should have been massive enough to
retain the iron-enriched ejecta of supernova (SN) explosions, and possibly experienced multiple bursts
of star formation. As a consequence, they are expected to host multi-iron and multi-age sub-
populations.
Two of these remnants (disguised as genuine GCs: Terzan5 and Liller1 have been recently discovered
(Ferraro et al., 2009, Nature,462, 483) and Liller1 (Ferraro et al, 2021, Nat. Astr., 5, 311), in the bulge
of the Galaxy. These systems (1) are indistinguishable from genuine GCs in their appearance, (2) have
metallicity and abundance patterns incompatible with those of bulge GCs and well in agreement with
those observed in the bulge field stars, (3) host a dominant old stellar population (testifying that they
formed at an early epoch of the Galaxy assembly), (4) host at least one young stellar population,
several Gyrs younger than the old one (demonstrating their capacity of triggering multiple events of
star formation). It is important to emphasise that the multi-age components in both the BFFs
identified so far were discovered by analysing proper motion (PM) selected color-magnitude-diagrams
(CMDs) obtained by combining HST and AO-assisted ground-based IR images (acquired at ESO-
VLT and Gemini; see Fig.2). Here we propose to secure deep second-epoch Ks Gemini images of 11
GC-like stellar systems into the Galactic Bulge to assess their stellar populations thus finally
addressing their true nature. The discovery of other BFFs would add new crucial information on the
formation process(es) of the Bulge

Outline of the Project: In this framework we are using high-resolution and NIR capabilities of
GSAOI-GEMS at GEMINI, HST and JWST to secure multi-epoch observations of a sample of
globular cluster-like stellar systems in the Galactic Bulge in order to search for other BFFs. 12 hours
of observing time at GEMINI South telescope have been already allocated to this project.
With the final aim of providing the accurate characterization of the stellar populations in each of the
investigated stellar systems, the student will be in charge of the construction of high-quality
differential reddening corrected and Proper motion- selected color magnitude diagrams (CMDs).
Proper motions will be obtained from the analysis of multi-epoch observations: in particular the new
GEMINI data will provide second-epoch observations for a sample of 11 clusters already observed
with HST. Moreover, the combination of near-IR and optical images will provide the appropriate
characterization of the extinction law in the direction of each stellar system (Pallanca+19, ApJ,882,
159; Pallanca+21, ApJ, 917, 92). Note that an increasing number of studies is showing that the
extinction law can significantly vary along different directions toward the Bulge (e.g., Popowski
2000,ApJ, 528, L9; Nataf+2013,ApJ, 769, 88). Indeed, the correct determination of the extinction law
in the direction of each target is crucial, since it is the first, mandatory step for a proper correction of
differential reddening, and a solid characterization of the evolutionary sequences in the CMD and it
has direct impact on the determination of each stellar system distance.

Contacts: francesco.ferraro3@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project: Playing with the physics of Blue Stragglers

Supervisor: F.R.Ferraro Co-supervisors: B. Lanzoni, C. Pallanca, M. Cadelano

Scientific Case: GCs are among the most beautiful objects in the sky, but their importance goes far
beyond their magnificent appearance. They are the best example of simple stellar populations and
natural laboratories where properly testing the predictions of the stellar evolution theory. In addition,
the large number of stars and the extremely high stellar densities in their center make GCs ideal
laboratories to study the effects of dynamics on stellar evolution. In fact, from a dynamical point of
view GCs are the only astrophysical systems that, within the time-scale of the age of the Universe,
undergo nearly all the physical processes known in stellar dynamics, such as: gravothermal instability,
violent relaxation, energy equipartition, 2-body and higher order collisions, binary formation and
heating, etc. Hence GCs turn out to be key astrophysical laboratories for the simultaneous study of
stellar evolution and stellar dynamics, two aspects that cannot be addressed independently: physical
interactions between stars, as well as the formation and evolution of binary systems play a significant
role in the overall evolution of the clusters and can considerably modify the observable properties of
their stellar populations. Blue Straggler Stars (BSSs) are the most abundant product of this dynamical
activity.

Outline of the Project: Being more massive

than normal cluster stars, BSSs are thought to
form either from mass-transfer processes in
binary systems or by stellar mergers induced by
direct collisions. They also are the brightest and
most numerous massive stars in old clusters.
Hence BSSs represent the best probe particles
for tracing the dynamical history of stellar
systems, but their nature and properties are still
largely unexplored. By means of a large
photometric and spectroscopic database
collected by our group (see the Figure), we plan:
(i) to measure the BSS physical parameters (i.e.
mass, gravity, temperature) of the entire
photometric sample comprising more than 4000
BSSs; (ii) to measure the rotation velocity of a
sample of BSSs in different environments
(clusters with different densities); (iii) to search
for chemical signatures of their formation mechanism, thus eventually unveiling their true nature; and
(iv) to determine their radial distribution over the entire cluster extension in a number of Galactic GCs
with different properties (central density, concentration, mass, etc). Indeed the level of segregation of
these stars has been found to be a powerful indicator of the level of dynamical evolution suffered by
the parent cluster (thus defining the so-called “dynamical clock” see Ferraro et al, 2012, Nature,
492,393; Ferraro et al. 2018, ApJ, 860, 26; Lanzoni et al., 2016, 833, L29, Ferraro et al., 2019,
Nature Astronomy, 3, 1149, Ferraro et al., 2023, ApJ, 950,145).

Contacts: francesco.ferraro3@unibo.it
 PhD project in ASTROPHYSICS
Title of the Project: Probing the early history of the Milky Way formation with the chemical DNA
of Bulge stellar systems

Supervisor: F.R. Ferraro Co-supervisors: B. Lanzoni, C. Pallanca, L. Chiappino Collaborators: L.

Origlia (INAF), C. Fanelli

Scientific Case: While observations of the distant Universe show that bulges of spiral galaxies form
through multiple mergers of massive clumps of gas and stars, and are subsequently enriched by
accretion events, no direct evidence of these processes has been found so far in the Milky Way Bulge.
Still, the Galactic Bulge is the sole spheroid where individual stars can be observed, allowing a unique
exploration of the debris of those primordial clumps and accreted structures. Indeed, the discovery that
Terzan5 (Ferraro et al., 2009, Nature,462, 483) and Liller1 (Ferraro et al, 2021, Nat. Astr., 5, 311), two
Bulge systems with the appearance of globular clusters (GCs), host multi-age and multi-iron
populations, and share the same “chemical DNA” of Bulge stars strongly suggest that they could be
Bulge Fossil Fragments (BFFs), the remnants of the proto-Bulge formation process. Thus, a variety of
relics tracing different phenomena are expected to populate the Bulge: BFFs, in-situ formed and
externally-accreted GCs, and also nuclear star clusters of cannibalized structures. Each system could
provide a piece of information about the Bulge formation and evolutionary history. The signatures of
the different origins are imprinted in the kinematic, photometric, and chemical properties of these
stellar systems, and can be read with different levels of accuracy.

Outline of the Project: In particular, the chemical tagging is a very powerful tool to unveil the true
nature and origin of stellar systems, because specific abundance patterns provide authentic “chemical
DNA tests” univocally tracing the enrichment process, hence the environment where the stellar
population formed. In fact, the atmospheres of the stars that we observe today preserve memory of the
chemical composition of the interstellar medium (ISM) from which they formed, and the chemical
abundances of the ISM vary in time if more than one burst of star formation occurs, owing to the
ejecta of each stellar generation. Thus, stars formed at different times and in environments with
different star formation rates (SFRs) have different chemical compositions, and by analysing the
chemistry of each stellar population one can univocally trace the enrichment process of the ISM.
Different abundance patterns are expected depending on the stellar polluters, the enrichment timescale
and the SFR, with a few specific abundance patterns being so distinctive that they can be used as
“DNA tests” of the stellar population origin.
In this framework we are leading a Large Programme at the ESO-Very Large Telescope (VLT) which
exploits the superb performances of the spectrograph operating in the near-IR CRIRES+ to perform an
unprecedented chemical screening of a representative sample of Bulge stellar systems, with the aim to
determine their chemical DNA and finally unveil their true origin. A total of 255 hours of observing
time was assigned to this Large Programme (PI: Ferraro).

The student will be in charge of the spectroscopic analysis of the high-resolution CRIRES spectra to
derive chemical abundances of several key elements. In particular, beyond the iron, the abundance of
many iron-peak elements (like Zinc, Vanadium, etc) and alpha-elements (like Calcium, Silicon,
Magnesium, Titanium) will be derived. These abundances will be used to construct powerful chemical
DNA indicators as the ‘classical” [a/Fe]–[Fe/H] diagram and to test the new-defined DNA test
involving [V/Fe] and [Zn/Fe] ratios. The combination of these test will allow a solid distinction
between in-situ formed and accreted GCs and the univocal identification of the environment in which
the stellar systems formed.

Contacts: francesco.ferraro3@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project: Unveiling the physics of Globular cluster cores

Supervisor : F.R. Ferraro Co-supervisors: B. Lanzoni, M. Cadelano, C. Pallanca

Scientific Case: The Universe we live in is dominated by darkness. Indeed, the vast majority of the
matter (and possibly of the energy) in the Universe is dark, while only a few percent can be revealed
through light signals. Fortunately the presence of dark matter (DM) leaves imprints in the kinematical
properties of the luminous mass, revealing invisible structures as DM halos and super-massive black
holes. This project is devoted to study the kinematics of sub-galactic stellar systems with the aim of
unveiling and probing the existence of non-visible matter at the globular cluster (GC) scales. Finding
DM halos in sub-galactic structures would be crucial to alleviate the cosmological "missing satellite
problem". Identifying intermediate-mass (103-105 M¤) black holes (IMBHs) in GCs could shed new
light on the formation processes of the SMBHs observed in galaxies and AGNs already at redshift z>6.
Precisely determining the internal structure and kinematics of GCs would also fill our current lack of
knowledge about the physics of these stellar systems, which are true astrophysical milestones.

Outline of the Project: To address these issues we propose to perform the most comprehensive study
ever attempted to determine the internal structure and kinematics of GCs. Specifically, we propose to
determine the projected density distribution, the velocity dispersion profile and the rotation curve, from
the very center out to the tidal radius and through unbiased methodologies, for a sample of 36 Galactic
GCs well representative of different structural parameters, dynamical stages and environmental
conditions. The line-of-sight (LOS) kinematics will be determined from the spectra of several hundreds
individual stars located along the entire extension of each GC, by exploiting state-of-the-art technology
in a non-conventional way. The data needed to perform this part of the project are already acquired by
means the ESO Multi-Instrument Kinematic Survey (MIKiS) that consists of 2 Large Programmes at
the ESO-VLT (PI: Ferraro, for a total of 300 hours of observing time). We combine: (i) Adaptive Optics
(AO) Integral Field Spectroscopy (IFS) in the innermost cluster regions (arcsecond scale), (ii) seeing-
limited IFS for the intermediate radial range (tens of arcsecond scale), and (iii) wide-field multi-object
spectroscopy for the most external regions (from one to tens arcminute scales).
A detailed presentation of the survey and first results can be found in: Ferraro et al., 2018, ApJ, 860, 50;
Ferraro et al., The Messenger, 172, 18; Lanzoni et al., 2018 ApJ, 865,11; Lanzoni et al., 2018, 860, 95.

PROPER MOTIONS - Accurate proper motions (PMs) of individual stars in the center of each GC will
be computed from multi-epoch HST images. This will provide us, for the first time, with the 3D
kinematics of dozens of central stars, thus allowing us to reconstruct their orbits and recognize possible
high-velocity objects accelerated by an IMBH. Moreover, we will properly sample the very central
regions, where the most interesting dynamical processes are expected to occur (but where PMs of stars
below the main sequence turnoff are not precisely measurable in most GCs because of crowding; see
Watkins et al. 2015, ApJ 803, 29). This is crucial to detect possible central LOS velocity dispersion
cusps. The PMs released by the GAIA space mission will complement this information in the external
cluster regions, thus providing us with the 3D cluster kinematics along the entire radial extension.

Contacts: francesco.ferraro3@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project: AGN feeding-feedback cycle in cool core clusters with Hα nebulae

Supervisor : Myriam Gitti (DIFA), Fabrizio Brighenti (DIFA)

Co-Supervisor : Francesco Ubertosi (DIFA)

Scientific Case:
In the absence of a heating source, the intra-cluster medium (ICM) at the center of the so-
called ‘cool core’ galaxy clusters should cool, condense, and accrete onto the brightest
cluster galaxy (BCG) and form stars. The end products of cooling, as inferred e.g., from Hα
nebulosity, are observed in many BCGs in the forms of cold molecular clouds and star
formation, but in quantities at least an order of magnitude below those expected from
uninterrupted cooling over the age of clusters (e.g., Peterson & Fabian 2006, Phys. Rep.,
427, 1). The implication is that the central gas must experience some kind of heating to
balance cooling. The most promising heating candidate has been identified as feedback
from energy injection by the central active galactic nucleus (AGN), manifesting in highly
disturbed X-ray morphologies (cavities,
filaments, shocks and ripples) which often
correlates with the morphology of radio jets
and lobes (e.g., McNamara & Nulsen 2007,
ARA&A, 45, 117; Gitti et al. 2012, AdAst).
This so-called ‘radio-mode’ feedback has a
wide range of impacts, from the formation of
galaxies to the regulation of cool cores, and
can in principle explain why cooling and star
formation proceed at a reduced rate.
However, the details of how the feedback loop
operates are still unclear.

Outline of the Project:

To clarify the regulation of the feeding and feedback cycle in cluster cores, it is crucial to
perform accurate studies of the cooling and heating processes for a sensible sample of
clusters with a prominent cold ICM phase. We have identified a sample consisting of the
X-ray brightest, most Hα luminous clusters visible from the Jansky Very Large Array
(JVLA). In particular, we selected clusters from the ROSAT BCS sample with 0.1-2.4 keV
flux fX>7x10−11 erg cm-2 s−1 and Hα luminosity >1040 erg s−1 . Visibility from JVLA ensures
that high resolution radio observations can be used to examine the interaction between
radio-loud AGN, ICM and cooling gas. The sample includes some very well-studied
systems (e.g., A1835, A1795, A2052), as well as clusters never observed in X-rays and/or
with only snapshot radio data (e.g., A1668). In the past years we obtained snapshot
Chandra and new JVLA data for three clusters which lacked archival X-ray and radio data.
Our first results (see Figure) suggest that, in some systems with disturbed morphology
showing spatial offsets between the BCG and different gas phases, the cooling process is
not currently depositing gas onto the BCG core (Pasini et al. 2019, ApJ, 885, 111; Pasini et
al. 2021, ApJ, 911, 66; Rosignoli et al. 2024, ApJ, 963, 8).
The aim of the PhD project is to investigate the feeding-feedback cycle of these
strongly cooling clusters and determine whether in systems with spatial offsets the
cycle is broken, or if the AGN activation is somehow maintained, for example being
driven by the periodicity of the gas motions (sloshing).
We have undertaken an observational campaign to acquire Chandra deep exposures and
multi-wavelength follow-up observations: in particular, we recently obtained new
Atacama Large Millimetre Array (ALMA) CO observations of the clusters A2495, A2207
and A478, as well as MUSE observations of the Hα nebulae in the cluster ZwCl235. The
PhD candidate will perform accurate analyses of the ALMA, Chandra, JVLA and MUSE data
already in hand, that will be complemented by the Hα and CO observations from literature
and ALMA archive, to determine the properties of the ICM and the warm gas and the
morphology and spectral indices of the central radio sources.

To obtain a good-quality multi-wavelength coverage for the whole sample, the PhD
candidate will propose for deeper Chandra and JVLA data of those clusters that only have
snapshot observations, to be able to perform a thorough investigation of the range of
cooling morphologies and interplay with the radio AGN in these clusters. The student will
also propose for complementary follow-up ALMA CO and MUSE observations to obtain
detailed information on the distribution and kinematics of the molecular gas (as done in
e.g., Russell et al. 2019, MNRAS, 490, 3025) and optical nebulae (e.g., Olivares et al. 2019,
A&A, 631, A22). Depending on the student interest, numerical simulations can further be
developed to compare the observed data with detailed computational modeling tailored
to the specific targets. Comparing these with the X-ray and radio data will allow us, as the
final goal of the project, to test key correlations between the different gas phases (plasma
- warm - molecular), thus leveraging a multi-frequency approach to investigate the link
between the hot ICM, optical filaments and molecular gas within cool cores, and to analyze
in detail star formation in the BCG.

Figure - The results from our snapshot Chandra (color map) and 1.4 GHz JVLA observations (green
contours) of A1668 indicate that this cluster has a disturbed morphology, showing hints of cavities (A,
B and C in the left panel) and spatial offsets between the X-ray peak, the radio BCG and the Hα line
emission (in the right panel, the cyan cross is the BCG center, the red and white crosses are the X-ray
and Hα peaks, respectively, and the black contours show the Hα line emission). These offsets suggest
that the current locus of greatest cooling in the hot ICM is separated from the central galaxy nucleus
and raise the question of whether they can affect the feedback cycle. From Pasini et al. 2021, ApJ, 911.

Contacts: myriam.gitti@unibo.it, fabrizio.brighenti@unibo.it, francesco.ubertosi2@unibo.it

 PhD project in ASTROPHYSICS

Title of the Project: Radio and X-ray connections in cool core galaxy clusters

Supervisor: Myriam Gitti (DIFA)

Co-Supervisors: Francesco Ubertosi (DIFA), Fabrizio Brighenti (DIFA)

Scientific Case:
Relativistic particles and magnetic fields permeating the intracluster medium (ICM) of
galaxy clusters are best traced by diffuse radio sources extending for hundreds of kpc
(Feretti et al 2012, A&AR; Van Weeren 2019, SSRv). In cool-core galaxy clusters
(characterized by a central temperature drop and no signs of recent mergers, e.g., Hudson
et al. 2010 A&A) it is possible to find “radio phoenices” and “radio mini-halos”.

Radio phoenices are extended sources possibly linked to old episodes of activity of
cluster-central radio galaxies. The electrons powering the radio emission are thought to
have been re-energized by compression due to
X-ray image (Chandra)
turbulence in the ICM. The fossil plasma has an 330 MHz GMRT contours
ultra-steep spectrum (𝛼 ≈ 2, with flux density
𝑆() ∝ −𝛼 ), suggestive of synchrotron aging,
and usually has a complex morphology
(de Gasperin et al. 2015, MNRAS; Mandal et al.
2020, A&A). Despite their importance to
understand the interplay between thermal and
non-thermal phenomena in galaxy clusters,
very few sources of these kind are known.
Mini-halos show steep spectra (1 ≤ 𝛼 ≤ 1.5)
and amorphous shapes, and typically extend to
100 - 200 kpc from the center (e.g., Gitti et al.
2004, A&A; Feretti et al 2012, A&AR). Their
origin is still unclear; among several models, it 200 kpc
has been proposed that ICM oscillations
(“sloshing”) in the cluster potential might
power the non-thermal radio emission (e.g., Figure 1: X-ray Chandra image of the cool core cluster
Zuhone et al. 2016, JPlPh), since mini-halos Abell 496, with 330 MHz GMRT contours overlaid in
typically appear confined within the sloshing white showing the central radio galaxy. Despite the
vigorous, ongoing sloshing of the ICM, which produced
cold fronts (e.g., Giacintucci et al. 2019, ApJ). three cold fronts (white arrows), the existing radio
Alternatively, active galactic nucleus (AGN) observations fail to reveal a mini-halo (adapted from
feedback may also provide turbulent re- Ubertosi et al., 2024, A&A). The PhD candidate will
search for a mini-halo with new sensitive JVLA and
acceleration due to the jets inflating bubbles MeerKAT observations.
and driving shock waves in the plasma (e.g.,
Bravi et al. 2016, MNRAS). A third possibility is a combination of the two: the main driver
for the creation of mini-halos could be AGN activity injecting turbulence and relativistic
particles in the ICM, while sloshing motions would drive the overall shape of the mini-
halos (Richard-Laferrière et al. 2020, MNRAS). The only way to discriminate between the
different scenarios is a multifrequency study of these sources: sensitive and resolved
radio observations can constrain the properties of mini-halos, while X-ray analysis of the
ICM can probe the process injecting turbulence in the clusters' hot medium.
Outline of the Project:
To understand the thermal and non-thermal interplay in cool core clusters, it is crucial to
combine X-ray data, that probe the thermal properties of the cluster environment, with
multi-frequency radio data of radio phoenices and mini-halos, that probe the properties
of the non-thermal components of the ICM (relativistic particles and magnetic fields).
The aim of the PhD project comprises two parallel investigations:
1. Clarify the formation channels of mini-halos: our group has been a leader research
team in the field for two decades, providing both theoretical models and pioneering
observational studies (Gitti et al. 2002, 2004, A&A) up to more recent investigations
(Gitti et al. 2018, A&A). Recently, we investigated AGN activity and diffuse radio
emission in Abell 496, a low-mass galaxy cluster that hosts one of the most spectacular
sloshing cool cores seen in the X-ray, and yet it showed no mini-halo in past
observations (Ubertosi et al. 2024, A&A; see Fig. 1). The central cluster galaxy
experienced repeated episodes of past AGN activity in the form of two steep-spectrum
radio lobes - an abundant source of seeds for reacceleration. The PhD candidate will
use recently acquired sensitive JVLA (1 – 2 GHz) and MeerKAT (0.8 – 1.7 GHz)
observations of Abell 496, in combination with archival X-ray and radio data, to: (a)
search for a possible faint minihalo in this cluster; (b) verify the sloshing/minihalo
connection for clusters of lower masses; (c) understand the possible role of the central
radio galaxy in seeding the ICM with relativistic particles.
2. Trace the thermal and non-thermal interplay using radio phoenices: revived
synchrotron sources are excellent probes of reacceleration mechanisms. Our group
has worked on different examples of these sources by combining X-ray and radio
observations (mainly Chandra, XMM-Newton, JVLA, GMRT and LOFAR, e.g., Ubertosi et
al. 2021, MNRAS; Ignesti et al., 2020b, A&A; Rotella et al. 2025, A&A). A recent case is
the galaxy cluster Abell 795, that hosts a 200 kpc diffuse radio source with an ultra-
steep spectrum (𝛼 = 2.2). The PhD candidate will have the opportunity to analyze new
deep Chandra observations (270 ks) of the ICM in Abell 795 as well as new multi-
frequency JVLA data (1 – 2 GHz and 4 – 6 GHz), finally allowing us to understand the
connection between the thermal gas of the cluster and the non-thermal plasma
constituting the candidate radio phoenix (Rotella et al. 2025, A&A). We also identified
other cool cores with X-ray and radio observations that reveal candidate radio
phoenices with ultra-steep radio spectra. The PhD candidate will analyze the existing
observations to measure the morphological and spectral properties of these sources,
as well as determine the dynamical state of their host clusters from X-ray data.

Overall, the PhD project is aimed at understanding the thermal and non-thermal interplay
in cool core galaxy clusters, which bears the information on the thermodynamic structure of
the ICM, magnetic fields, turbulent reacceleration efficiency, and relativistic particles. The
PhD candidate will measure spectral indices of the diffuse sources, determine radio and
X-ray morphologies, and derive ICM temperature, density, and pressure gradients. The
activities will be conducted in collaboration with international researchers. The PhD
candidate will also propose for X-ray (Chandra) and radio (JVLA, uGMRT, MeerKAT,
LOFAR) observations of candidate radio phoenices and mini-halos, to push forward the
knowledge of these objects and pave the way for future radio telescopes that are expected
to detect hundreds of these radio sources (as SKA; e.g., Gitti et al. 2018, A&A). They will
also propose for complementary follow-up XRISM observations to directly measure the
turbulence of the ICM and link this crucial information with the theoretical models of
turbulent reacceleration. Depending on the student interests, numerical simulations can
be developed to compare the observed data with detailed computational modelling.

Contacts: myriam.gitti@unibo.it, francesco.ubertosi2@unibo.it, fabrizio.brighenti@unibo.it

 PhD project in ASTROPHYSICS

Title of the Project: Leveraging Machine Learning to Decode Multiple Populations in

Stellar Clusters

Supervisor: Prof.ssa Carmela Lardo

Co-Supervisor: Prof. Alessio Mucciarelli

Scientific Case: Globular clusters (GCs) are crucial for understanding galaxy evolution,
yet the origin of their multiple populations (MPs) remains uncertain. These populations
exhibit distinct elemental abundances: some stars are enriched in He, N, and Na but
depleted in O and C, while others resemble field stars (Gratton et al., 2012). The first
population (P1) has typical chemical compositions, whereas the second (P2) is
enhanced in N and Na, likely due to material expelled by earlier generations of stars.
While self-enrichment models account for certain trends, they fail to fully reproduce
observations, highlighting the need for alternative explanations (e.g., Bastian & Lardo,
2018).

Outline of the Project: The HST's HUGS survey (Piotto et al. 2015) utilised
chromosome maps (CMs) to analyse MPs in 57 old Galactic GCs, employing specific
filters to trace their chemical composition and revealing correlations between P2
fractions, chemical variations, and GC mass (Milone et al. 2017). While highly effective,
CMs are resource-intensive and currently limited to the HUGS clusters and a few in the
Magellanic Clouds (Saracino et al. 2020). Their dependence on the F275W filter makes
them particularly demanding in HST time, restricting their use for reddened or distant
GCs. Moreover, their focus on cluster cores limits our understanding of sub-population
distributions, particularly in older GCs (Tiongo, Vesperini & Varri 2019).
Despite advances, understanding MPs requires ever-improving empirical data. Machine
learning (ML), with its pattern recognition capabilities, presents a breakthrough in this
area. This project pioneers ML for MP studies, leveraging multi-band imaging to estimate
stellar parameters and elemental abundances across GCs, bridging spectroscopy and
imaging for large-scale statistical analysis.
This project adopts a progressively sophisticated approach to deriving stellar
parameters and abundances. Initially, it explores approaches based on predicted
magnitudes and colors (Lardo et al. 2018). A more advanced phase incorporates
simulated space-based images from HST and JWST (e.g., Kuntzer, Tewes & Courbin
2016). Final ML models will be applied to previously unseen data, including photometric
catalogs and archival images. The results will enable statistical analyses of MP evolution
across time and parameter spaces, aiming to (i) uncover unexpected trends and (ii)
establish a foundation for future MP models.

Contacts: carmela.lardo2@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project: Decoding Multiple Populations - Bridging Star Formation Insights
Across Galactic Environments

Supervisor: Prof.ssa Carmela Lardo

Co-Supervisor: Prof. Alessio Mucciarelli

Scientific Case: Globular clusters (GCs), some of the oldest objects in the Universe, offer
key insights into star formation and galaxy assembly through their age, chemical, and
kinematic data. To fully utilize GCs in studying galaxy evolution, we must first
understand their formation processes. The chemical makeup of GC stars holds key
information about their origins and the early stages of galaxy formation. Once
considered simple stellar populations with uniform age and composition, GCs are now
known to host multiple populations (MPs) with variations in helium and light elements
such as C, N, O, Na, Mg, and Al, and in some cases, Fe (Milone & Marino 2022). Despite
extensive research, the origin of MPs remains uncertain (e.g., Bastian & Lardo 2018).

Outline of the Project: Observations suggest that MP-like chemical signatures extend
beyond GCs, appearing in dense stellar systems more broadly. Many Galactic Bulge stars
show MP-like chemistry, implying MPs exist beyond dissolved clusters (Schiavon et al.,
2017). Evidence of MPs has also been found in an ultra-compact dwarf (UCD; Strader et
al., 2013). Na variations in massive early-type galaxies (ETGs) suggest an unusual initial
mass function (IMF; Conroy & van Dokkum, 2012), but Na and N fluctuations linked to
MPs may mimic IMF differences. The UV upturn in ETG spectra further supports an MP
connection, likely influenced by He-enhanced horizontal branch stars.

The proposed project aims to determine whether MPs are unique to GCs or represent a
broader mode of star formation across various environments, potentially influenced by
observational biases. This will be achieved by developing Stellar Population Synthesis
(SPS) models that incorporate MP chemistry to assess their presence in UCDs and ETGs
and evaluate their impact on stellar system properties. This will be the first instance of
including MP chemistry in SPS models. Initial validation will focus on metal-rich GCs.
Future stages will compare models with high-quality galaxy spectra. The project will
develop SPS models that account for MP chemistry, enabling more accurate
interpretations of GC and galaxy properties, especially considering recent JWST
discoveries of lensed GCs at high redshift (Mowla et al., 2022).

Contacts: carmela.lardo2@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project: Searching for high redshift AGN with current and future X-ray
and radio facilities

Supervisor : S. Marchesi
Co-Supervisors : G. Lanzuisi, R. Gilli, A. Comastri

Scientific Case:
This project aims to develop effective methods for identifying the elusive high redshift
and obscured Active Galactic Nuclei (AGN) population, to advance our understanding of
the formation and evolution of supermassive black holes (SMBHs) and galaxies in the
early Universe. By combining the physical properties of accreting SMBH contained in
state-of-the-art cosmological simulations and the observed relations beteen accretion
and emission in different bands, the project will produce X-ray and radio mock catalogs
of AGN. These will be tested and improved against existing/ongoing deep and wide X-ray
and radio surveys (COSMOS, CDFS, J1030, XMM-LSS etc). These mocks will then be used
to optimize survey strategies for future observations with next-generation facilities,
including the Square Kilometer Array Observatory (SKAO), and X-ray missions such as
ESA’s next large X-ray mission NewAthena and the proposed NASA mission AXIS.
Ultimately, this research will enhance our understanding of the first SMBHs and their
role in shaping the early Universe while maximizing the scientific impact of forthcoming
flagship observatories.

Outline of the Project:

The student will analyse the physical processes that govern SMBHs evolution and
accretion in cosmological simulations - such as BH seeding, accretion histories and spin
evolution - and assess their impact on the observable properties of high-redshift AGN.
The student will define a set of physically-motivated criteria for effectively selecting
obscured AGN at high redshift, and then test and refine these selection criteria using
data from current/ongoing deep X-ray and radio surveys, in which the host institutions
play a leading role: the team is directly involved in the ongoing COSMOS-WebX Chandra
Large Program that will more then double the X-ray sensitivity of the central 0.5 deg2
covered by a variety of deep multi-wavelength data sets, including the JWST COSMOS-
Web NIRCam and MIRI survey.

These refined selection criteria will then be applied to optimize the observations and
selection strategies for future observatories such as SKAO in the radio and Athena and
AXIS in the X-rays. The team is deeply involved in the development of Athena with
several Study Team Working Group members, while the supervisor is directly involved
as a Co-Investigator of the AXIS study team.

Contacts: stefano.marchesi@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project: Characterizing the emission mechanisms of extreme high

synchrotron peak blazars: towards a new population of CTAO extragalactic emitters

Supervisor: Stefano Marchesi (DIFA)

Co-Supervisors: Cristian Vignali (DIFA)

Scientific Case: Blazars are accreting supermassive black holes (SMBHs), or active
galactic nuclei (AGN), whose relativistic jets are pointed in the direction of the observer.
Their spectral energy distribution (SED) is characterized by two clear bumps: the first
one at lower frequencies/energies, the so-called ``synchrotron peak'', where the
synchrotron emission is caused by the relativistic electrons in the jets. The second one at
higher frequencies/energies, the ``inverse Compton'' (IC) one, is instead caused by the
interaction and subsequent up-scattering in frequency of the synchrotron-produced
photons with the same relativistic electrons. The most extreme class of blazars are the
so-called “Extreme High Synchrotron Peak” (EHSP) blazars, whose synchrotron peak is
observed in the X-ray band, and the IC peak in the Very High Energy (VHE) band, in the
GeV-TeV regime that will be observed with unprecedented sensitivity by the forthcoming
Cherenkov Telescope Array Observatory (CTAO). A full characterization of the properties
of EHSP sources is thus timely, to inform the observing strategy of the CTAO surveys, as
well as to select promising candidates for targeted follow-up campaign

Outline of the Project: The main goals of the proposed PhD project are (a) Select targets
of interest among a population of X-ray bright EHSPs that lack a counterpart in the
Fermi-LAT 4FGL catalog (in the MeV-GeV band). Such sources, while missed by
Fermi-LAT, could represent a sample of objects whose SED will peak in the TeV band, and
will thus be detected by CTAO; b) Use available X-ray observations from multiple X-ray
telescopes (NuSTAR, XMM-Newton, Chandra, Swift-XRT, eROSITA…) to put constraints on
the SED at the synchrotron peak, and consequently obtain information on the physical
mechanisms behind these extreme emitters; c) Use state-of-the-art models of blazar
emission (e.g., AGNPy, JetSet) to make predictions on the shape of the SED in the CTAO
energy range, testing a variety of parameters and models. These results will be used to
select promising candidates for follow-up observations with CTAO, as well as with
current generation Cherenkov telescopes (in particular, the MAGIC-LST1 ones).

The PhD candidate will be trained in the selection and characterization of blazars,
fully exploiting the wealth of multi-wavelength data currently available. They will learn
how to handle, analyze, and interpret multi-band data, and will gain expertise in
proposal writing and presenting the work at international conferences. They will also
have the chance of spending a period of time abroad and in other Italian institutions,
working with collaborators of the advisors on the topics reported above..
Contacts: stefano.marchesi@unibo.it; cristian.vignali@unibo.it.
 PhD project in ASTROPHYSICS

Title of the Project: The effects of baryonic physics implementation in simulations of galaxy
formation and evolution using Lagrangian and mesh-based hydrodynamic codes

Supervisor: Federico Marinacci

Scientific Case: Modern numerical simulations of galaxy formation and evolution have
achieved remarkable accuracy in reproducing observed galactic properties across various
spatial scales. This success largely stems from the ability of simulations to regulate and
quench star formation through highly efficient stellar and AGN feedback mechanisms.
However, the implementation of these feedback processes must be adapted to the specific
numerical code employed and in particular to the method used to model the hydrodynamic
evolution of gas. Two primary approaches are used to follow hydrodynamics in galaxy
formation simulations: smoothed particle hydrodynamics (SPH) and mesh-based methods.
While differences in simulation outcomes are often attributed to variations in feedback
implementations rather than the choice of hydrodynamic technique, it remains unclear
whether a specific implementation of feedback processes works “universally” – that is
independent of the hydrodynamic method adopted – or if they introduce or mask inaccuracies
inherent in the hydrodynamic solver. These uncertainties significantly limit the predictive
power of simulations and hinder a comprehensive theoretical understanding of the physical
mechanisms shaping galaxies. Addressing these modeling challenges is crucial to building a
coherent and reliable theoretical framework for galaxy formation and evolution.

Outline of the Project: This PhD project aims to investigate the impact of baryonic physics
implementations by employing and extending the SMUGGLE model—an advanced
interstellar medium (ISM) and stellar feedback framework—currently integrated into the
moving-mesh code Arepo. The first objective is to adapt and implement the SMUGGLE
model within the SPH-based code Gadget4. By incorporating the same galaxy formation
physics module into two codes that share the same treatment of gravitational dynamics but
differ in their modelling of hydrodynamic, the project will provide critical insights into the
influence of numerical techniques on galaxy evolution predictions. Following this
implementation phase, the student will design, execute, and analyze state-of-the-art numerical
simulations of galaxy formation. Initial simulations will focus on isolated galaxies, gradually
scaling up to cosmological zoom-in calculations. The potential inclusion of AGN feedback in
cosmological simulations will also be explored. A key aspect of the analysis will be
comparing results from Arepo and Gadget4 to assess how different hydrodynamic approaches
interact with the underlying physics of galaxy formation, ultimately improving our
understanding of these complex processes.

Contacts: Federico Marinacci (federico.marinacci2@unibo.it)

 PhD project in ASTROPHYSICS

Title of the Project: Forecasting the gravitational wave signal in cosmological simulations
for current and upcoming cosmological surveys
Supervisors: Federico Marinacci (DIFA), Marco Baldi (DIFA)
Co-supervisors: Micol Bolzonella (INAF-OAS), Lucia Pozzetti (INAF-OAS)
Scientific Case: The detection of gravitational waves (GWs) by LIGO-VIRGO, along with
their optical counterpart, has opened a new window into the Universe. GWs can help
constrain cosmic expansion, complementing Type Ia supernovae. With optical counterparts
providing increasingly precise redshifts, GW-based methods may soon be competitive with or
even be superior to traditional cosmological probes. However, accurately determining the
distribution of GW events is essential for testing cosmological models and exploring physics
beyond the Standard Model. GWs originate from the mergers of compact binaries, which are
the end products of stellar evolution within the broader context of galaxy formation.
Consequently, predicting the distribution of GWs to forecast their cosmological signal
requires modeling highly non-linear astrophysical and cosmological processes. This can only
be achieved through advanced numerical simulations combining large-scale structure
formation and small-scale stellar dynamics. Moreover, alternative dark matter models or
modified gravity theories could influence the evolution of cosmic structures, potentially
leaving observational signatures detectable in upcoming GW surveys. These surveys will then
become crucial for probing the physics of the dark sector. Recently, our group has developed
and implemented a novel method to populate large hydrodynamical galaxy formation
simulations (such as Millennium-TNG, the largest of its kind to date) with a self-consistent
distribution of GW sources. This approach, based on synthetic stellar evolution calculations,
has been integrated into the state-of-the-art hydrodynamical N-body code Arepo.

Outline of the Project: The PhD project aims to exploit this recently developed tool to build
large 3D catalogues of GW sources forming along (and consistently with) the underlying
history of galaxy formation predicted by state-of-the-art hydrodynamical astrophysical
models. Additionally, the project will develop methods to populate dark matter halo
catalogues, obtained from less computationally intensive collisionless simulations, with a
realistic distribution of GW events. These methods may range from simple statistical
mapping, such as in Halo Occupation Distribution (HOD) techniques, to more sophisticated
approaches including Machine Learning. A possible further goal of the project would be to
integrate the GW population model with well-established procedures for generating mock
galaxy catalogues from dark matter-only simulations. This integration would enable the
creation of self-consistent galaxy and GW catalogues for probe combination and cross-
correlation studies in view of the planned future synergies between large galaxy surveys (e.g.,
Euclid, VRO, Roman Space Telescope, etc.) and GW surveys from existing (Ligo-Virgo-
Kagra) or future (Einstein Telescope, Lisa) facilities.
Contacts: Federico Marinacci (federico.marinacci2@unibo.it), Marco Baldi
(marco.baldi5@unibo.it)
 PhD project in ASTROPHYSICS

Title of the Project:

Exploring Gravity Models with gravitational redshifts in galaxy cluster
environments

Supervisor: Prof. Federico Marulli

Co-Supervisor: Prof. Lauro Moscardini

Scientic Case:
Current and future wide-eld spectroscopic and photometric surveys (e.g., KiDS,
Euclid, LSST, WST) present a unique opportunity to signicantly increase the
number of known galaxy clusters and explore previously uncharted territories
at both low mass (M ~ 1014 Msun) and high redshift (z > 1). The scientic interest in
these new samples of galaxy clusters is twofold. Firstly, the abundance and
clustering of these structures provide crucial constraints on cosmology, as the
cluster population carries information about the statistical distribution of initial
0uctuations, their subsequent growth, and the dynamics of dark matter halo
collapse. Secondly, these clusters serve as invaluable laboratories for studying
the evolution of galaxies in dense environments across di1erent epochs.
Furthermore, galaxy clusters o#er natural cosmic laboratories for
conducting direct measurements of gravitational redshifts, enabling tests of
gravitational theories on megaparsec scales. Specically, the gravitational
redshift e1ect can be inferred from the distribution of peculiar velocities of
cluster member galaxies as a function of their transverse distance from the
cluster center. However, achieving the required precision for denitive tests of
General Relativity versus alternative gravity theories has been hindered by the
lack of su5ciently large and dense samples of galaxy clusters and associated
cluster member galaxies. This limitation is expected to be overcome with the
wealth of data from upcoming missions, such as the ESA Euclid telescope and the
NASA Nancy Grace Roman Space Telescope, and, in the future, by the planned
WST spectroscopic surveys.
The objective of the proposed PhD project is to leverage the new galaxy and
cluster spectroscopic samples expected in the near future to conduct novel tests
of gravitational theories using gravitational redshifts in galaxy clusters.
The PhD student will initially construct and characterize new spectroscopic
cluster catalogues, focusing on key properties such as cluster centers and the
positions of cluster member galaxies. New software tools will be developed to
compute these measurements and conduct the necessary statistical analyses.
The validity of these pipelines will be veried using simulated catalogues to
identify and address potential systematic uncertainties. The newly implemented
algorithms will be made publicly available through the CosmoBolognaLib, a
comprehensive suite of free software C++/Python libraries for cosmological
calculations. Ultimately, the PhD student will deliver new constraints on
gravitational theories, potentially distinguishing among various alternative
gravity frameworks.

Outline of the Project:

 Construction and characterization of new photometric and
spectroscopic catalogues of galaxy clusters and cluster member
galaxies from simulated and real data sets.
 Implementation of novel algorithms to measure and model the
peculiar velocity distributions of cluster member galaxies.
 Integration of the developed software into the CosmoBolognaLib.
 Investigation of all potential systematic uncertainties a1ecting the
analysis.
 Application of the model to real data sets to derive new constraints on
gravity theories.
 Application of the model to mock catalogues of next-generation missions
to provide forecasts for future analyses.

Contacts:
Federico Marulli (federico.marulli3@unibo.it)
Lauro Moscardini (lauro.moscardini@unibo.it)
 PhD project in ASTROPHYSICS

Title of the Project:

Cosmology with Bayesian deep neural networks to learn the properties of the
Cosmic Web

Supervisor: Prof. Federico Marulli

Co-Supervisors : Prof. Lauro Moscardini, Dr. Alfonso Veropalumbo

Scientic Case:
In the last decades, the exponential growth of data drastically changed the way
we do science. This data tsunami led Cosmology in the so-called Big Data Era.
Standard cosmological analyses based on abundances, two-point and higher-
order statistics of speci(c extra-galactic tracer populations – such as e.g.
galaxies, galaxy clusters, voids - have been widely used up to now to
investigate the properties of the Cosmic Web. However, these statistics can only
exploit a sub-set of the whole information content available.
The proposed PhD project aims to enhance the scienti(c utilization of current
and future galaxy surveys, taking advantage of the newest data analysis
techniques to assess the properties of the large-scale structure of the Universe.
Speci(cally, the goal is to develop new Bayesian deep neural networks for
cosmological analyses. The implemented supervised machine learning
infrastructure will be trained and tested on simulated catalogues in di1erent
cosmological frameworks, and then applied to current available data sets, such
as e.g. BOSS, eBOSS, DESI. In the next future, the developed neural network
will be used to analyse the data provided by the ESA Euclid satellite.
The primary scienti(c goals of this PhD project are to provide independent
constraints on the dark energy equation of state parameters and to test
Einstein’s General Theory of Relativity. The PhD student will acquire high-
level knowledge on the modern statistical techniques to analyse large extra-
galactic data sets and extract cosmological information. Moreover, he/she will
become familiar with the latest deep learning techniques for data mining,
which will be explored for the (rst time in a cosmological context. The new
implemented algorithms will be included in the CosmoBolognaLib, a large set
of free software C++/Python libraries for cosmological calculations.
Outline of the Project:
The PhD project is organised in the following phases:
 Construction of a large set of dark matter mock catalogues in
di+erent cosmological frameworks using fast techniques, such as the
ones based on Lagrangian Perturbation Theory.
 Application of subhalo abundance matching (SHAM) and/or halo
occupation distribution (HOD) techniques to populate the dark matter
catalogues with galaxies and galaxy clusters.
 Implementation of new standard and Bayesian deep neural network
infrastructures.
 Training and testing of the neural networks on mock galaxy and cluster
catalogues.
 Comparison of the cosmological constraints from neural network
and standard probes, such as e.g. the ones from 2-point and 3-point
correlation functions of galaxies and galaxy clusters.
 Utilization of the new machine learning tools on available data sets
to derive independent cosmological constraints.
 Application of the tools on larger mock catalogues to provide forecasts
for next-generation galaxy redshift surveys.

Contacts:
Federico Marulli (federico.marulli3@unibo.it)
Lauro Moscardini (lauro.moscardini@unibo.it)
Alfonso Veropalumbo (alfonso.veropalumbo@uniroma3.it)
 PhD project in ASTROPHYSICS

Title of the Project:

Cosmological exploitation of the statistical properties of Cosmic Voids

Supervisor: Prof. Federico Marulli

Co-Supervisors: Dr. Soa Contarini, Prof. Lauro Moscardini

Scientic Case:
A signicant fraction of the Universe volume is made up of almost empty space
regions, that emerge between the laments and the walls of the Cosmic Web.
These low-density patches of the Universe are known Cosmic Voids and
provide one of the most powerful, though yet largely unexplored, cosmological
probes. Thanks to their huge sizes – up tens of megaparsec - and low-density
interiors, voids constitute unique cosmic laboratories to investigate the
physical properties of dark energy, as well as modied gravity theories,
massive neutrinos, primordial non-Gaussianity and Physics beyond the
Standard Model. The current and upcoming spectroscopic galaxy surveys will
,ood us with a huge volume of data, allowing us to signicantly enlarge the
cosmic void catalogues currently available, up to large redshifts. Cosmic voids
are now being recognized as core cosmological probes in next-generation
experiments.
This PhD project is aimed at fully exploiting the primary large-scale statistics of
the cosmic void population, that is the size function, the density and lensing
proles, and the spatial clustering of voids. The PhD student will rstly
investigate di.erent void detector algorithms, with the goal of maximizing the
purity and completeness of the void samples, as well as to accurately
characterize the sample selections. Standard statistical methods, as well as the
newest Machine Learning techniques will be considered to optimize the data
analysis pipelines. New simulated catalogues of cosmic voids shall be
constructed in di.erent cosmological scenarios to test the e0ciency of the void
detectors and check for systematic uncertainties in the cosmological analysis.
The PhD student will then analyse real data sets and provide new cosmological
constraints from the probe combination of the main cosmic void statistics. The
catalogues will be extracted from both current data sets, such as the nal SDSS-
III BOSS survey, and ongong galaxy spectroscopic and photometric samples, as
the ones from the ESA Euclid mission.
Outline of the Project:
The PhD project is organised in the following phases:
 Implementation of new void detector algorithms, including Machine
Learning based methods, and comparison with existing available codes.
 Implementation of new software tools to measure all primary
statistics of cosmic voids: size function, lensing proles, void
clustering.
 Implementation of likelihood modules to extract cosmological
information from single void statistics and probe combinations.
 Test of the data analysis pipelines on mock void catalogues extracted
from standard and beyond-ΛCDM cosmological simulations.
 Construction of new real cosmic void catalogues.
 Cosmological analysis on real cosmic void catalogues.
 Forecasting the constraining power of next-generation photometric and
spectroscopic void samples.

Contacts:
Soa Contarini (soa.contarini@unibo.it)
Federico Marulli (federico.marulli3@unibo.it)
Lauro Moscardini (lauro.moscardini@unibo.it)
 PhD project in ASTROPHYSICS

Title of the Project: The Properties of Strong Gravitational Lenses

Supervisor: Prof. Robert Benton Metcalf

Co-Supervisors : Prof. Giulia Despali

ScientiBic Case:
The Euclid space telescope has become the world's
best strong gravitational lens-Binding machine. It
has already found hundreds of gravitational lenses
and is expected to discover hundreds of thousands
over the next few years. Traditionally, these
spectacular objects have been studied individually
or in samples of just a few. These studies have made
discoveries about dark matter, the structure of
galaxies, and cosmology. With Euclid, we move into
a new regime where the number of lenses is very
large, but the information about each one is limited. For the Birst time, we will be able to
use statistically signiBicant samples of the lenses to probe how the distribution of dark
matter around galaxies is related to their observable properties. However, to do this, we
must overcome some signiBicant challenges involving the bias introduced by the
methods used to detect the lenses. Current methods involve Convolutional Neural
Networks (CNNs) and crowd-sourced human inspection. These miss some lenses and
misclassify others.

Outline of the Project:

The project involves turning the observations of thousands of individual gravitational

lenses into constraints on the nature of dark matter, galaxy formation, and cosmology.

Over the past several years, a pipeline for producing realistic simulated images of
gravitational lenses has been developed. This pipeline will be further developed to make
the images more realistic.

Calibrate the detection algorithms by running them on the simulated images. This
involves collaborating with many members of the Euclid collaboration, who are
developing Machine Learning (ML) methods for lens detection and modeling.

Develop a simulation-based statistical method for characterizing the selection and for
inferring statistical characteristics of the gravitational lens population. For example,
how the distribution of dark matter depends on the galaxy type and redshift. Compare
these results to the predictions of theories of dark matter and cosmology.

This project involves computer programming and developing machine learning methods.

Contacts: robertbenton.metcalf@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project: Stars as laboratories for testing fundamental physics

Supervisors : Andrea Miglio (DiFA, UniBo), Oscar Straniero (INAF-OAAb)

Scienti=ic Case:

The high temperature and density that develop within the cores of evolved stars, from
red giants to supergiants, make them ideal sites to investigate deviations from the
standard models describing the behaviour of matter in extreme conditions, which are
often not accessible by current laboratory experiments.

In this context, a growing amount of scientiIic papers discuss peculiar properties of

hypothetical weakly interacting particles, by comparing stellar models predictions to
several astronomical observables.
For instance, axions are pseudo-scalar particles predicted by several non-standard
theories. They provide the most elegant solution to the so-called strong CP problem, i.e,
the conservation of the charge-parity symmetry in processes that involve strong
interactions. If they exist, axions may have a great impact on cosmology (they are good
dark matter candidates) and on stellar evolution. Indeed, they may be produced in hot
stellar interiors through their coupling with standard particles, like photons or
electrons. In this framework, the most stringent constraints to the strength of the axion-
photon coupling comes from the lifetime of core-helium-burning stars (Ayala et al.,
2014), while the most stringent constraint to the axion-electron coupling is provided by
the luminosity of the red-giant tip (Straniero et al., 2020; Capozzi & Raffelt, 2020). In
addition to axions, other feeble particles, e.g., dark photons, may also be produced by
thermal processes in stellar interiors and, hence, probed with this technique. The same
method may also provide hints on the electromagnetic properties of standard particles,
e.g. the neutrino magnetic moment (Capozzi & Raffelt, 2020).

The constraints obtained so far are, however, limited by the effective reliability of our
stellar models and by the scarce direct information we have on the internal structure of
stars. The situation has now changed, and detailed constraints on the internal structure
of red giants are now available thanks to the detection and interpretation of their
resonant oscillation frequencies (asteroseismology), offering a unique opportunity to get
important hints on various new-physics hypotheses.

Outline of the Project:

During the 3-yr project, the student will:
• Quantify the effect of non-standard particles on the internal structure and evolution of
red-giant stars and on their pulsational spectra. The student will familiarise with
stellar evolution and pulsation codes and, crucially, with the current uncertainties
pertaining to stellar modelling (year 1).
• Devise observational tests needed to set limits on the cross-section describing the
interaction of non-standard particles with stellar matter (year 2,3). These tests will
 explore both potential direct seismic signature of non-standard particles and indirect
signatures that are expected to become signiIicant as a result of reducing, thanks to
seismic constraints, other uncertainties in current models (e.g., extension of the
convective core, core angular momentum).

The student will be involved in large international collaborations, in particular in the

ESA PLATO mission consortium (launch 2026 https://platomission.com/, https://
www.esa.int/Science_Exploration/Space_Science/Plato) and in the proposal of next-
generation asteroseismic missions such as HAYDN (http://www.asterochronometry.eu/
haydn/)

The nature of the project is such that the student should be happy coding and
interpreting results from numerical simulations of stellar evolution, analysing and
manipulating data. Familiarity with stellar evolution would be highly beneIicial.

Contacts:

Prof. Andrea Miglio Prof. Oscar Straniero

andrea.miglio@unibo.it oscar.straniero@inaf.it
https://www.unibo.it/sitoweb/andrea.miglio
https://www.asterochronometry.eu
 PhD project in ASTROPHYSICS

Title of the Project: Exploiting Gravitational Waves as cosmological probes in view of

the new upcoming large GW and galaxy surveys

Supervisor : Michele Ennio Maria Moresco

Co-Supervisors : Andrea Cimatti

Scientific Case: Modern cosmology is currently undergoing an exciting yet problematic

time. After the discovery of the accelerated expansion of the Universe (Riess et al., 1998,
Perlmutter et al. 1999), many of the cosmological probes currently identified as ‘main’
(Cosmic Microwave Background, Baryon Acoustic Oscillations, Supernovae Type Ia)
experienced a period of continuous technological and theoretical development that lead
them to percent accuracy; however, as a consequence this lead to a tension between early-
and late-Universe measurements, that are currently pointing to values of cosmological
parameters at odds by more than 4 sigma (see e.g. Verde et al. 2019). It is therefore now
crucial to go beyond standard probes and explore alternative probes that can help to
resolve this tension. Gravitational waves (GW) are amongst the most promising emerging
cosmological probes in the near future (see Moresco et al. 2022). These astrophysical
phenomena provide us a clean measurement of the distance to the source completely
independent on cosmological models, only relying on General Relativity. However, to be
used as standard sirens, it is necessary to associate to these events a redshift, as firstly
proposed by Schutz (1986). This association can be either direct (bright sirens, as for the
case of GW170817) or statistical (as for the case of dark sirens, see e.g. Palmese et al.,
2021, LIGO Scientific Collaboration et al., 2021). In this Ph.D. Thesis, we propose to
explore techniques to maximize the scientific return of analysis of GW as cosmological
probes by improving on current analysis by including in the analysis new observational
features, exploring the constraints that can be set by current data, forecasting the impact
of the new upcoming large GW (e.g. Advanced LIGO-Virgo, Einstein Telescope, …) and
electromagnetic observatories (e.g. WST, …), and preparing a framework to be prepared
to analyze the expected new data by the LIGO/Virgo collaboration.

Outline of the Project: The field of GW cosmology has recently started and is gaining a
growing attention in the cosmological community. For this reason, many different aspects
are still worth exploring, especially in the use of GW as dark sirens, like the impact in the
derivation of cosmological parameters of the galaxy catalog used to cross-correlate the
EM counterpart of the GW, of the accuracy in the redshift estimates, of the completeness
of the catalog, of the assumed distribution of BBH masses, of extending the GR framework
in the analysis. While some seminal works are being recently published, it is crucial to
assess many of these aspects to establish GW as robust cosmological probes. At DIFA, we
recently developed a public GW analysis SW (CHIMERA, in collaboration with national
and international colleagues), and in this Ph.D. Thesis we propose to extend those by
including new features as discussed above, with the following goals: (i) integrate in the
GW code improved statistical models, (ii) study and characterize current public catalogs
(GLADE+, DESI, …), (iii) analyze the impact of different properties in the catalogs
(completeness, accuracy of the redshift estimates) on the cosmological parameters
accuracy, (iv) take advantage of the expertise at DIFA in generating mock galaxy catalog
(CosmoBolognaLib) to develop a framework to produce ad-hoc simulated galaxy catalogs
for GWs to forecast the performance of the combination of future spectroscopic surveys
(e.g. Euclid) and GW observatories (e.g. Einstein Telescope), (v) apply the developed
framework to current and simulated data, to provide forecasts on the constraints on the
expansion history of the Universe, also in combination with other cosmological probes.

Contacts:
prof. Michele Ennio Maria Moresco
Associate professor
Department of Physics and Astronomy – University of Bologna
address: via Gobetti, 93/2, 40129, Bologna
email: michele.moresco@unibo.it - phone: 051/2095775
 PhD project in ASTROPHYSICS

Title of the Project: Towards a comprehensive clustering analysis: maximizing the

scientific return through the combination of lower-order and higher-order correlation
functions in configuration and Fourier space

Supervisor : Michele Ennio Maria Moresco

Co-Supervisors : Massimo Guidi, Federico Marulli

Scientific Case: The analysis of the clustering of galaxies has recently become one of the
fundamental tools in Modern Cosmology to probe the distribution of Large Scale
Structure. It retains cosmological information of the primordial Universe in the form of
peculiar matter over-densities that appear around 100 Mpc/h. These features are called
baryon acoustic oscillations (BAOs), and can be used as standard rulers to constrain the
expansion history of the universe. In Fourier space, they appear as wiggles in the power
spectrum, P(k), while in configuration space, they appear as a distinctive peak around
r∼100 Mpc/h in the two-point correlation function (2PCF). For these reasons, since the
beginning of the century galaxy clustering has become one of the main cosmological
probes, and several spectroscopic surveys both from the ground (e.g. BOSS, eBOSS) and
from space (e.g. Euclid) have been developed to exploit it at its best.
Historically, the field has been divided into two approaches, either by working in Fourier
space (where the modelization is easier, but handling observational effects such as the
footprint is more complicated) or in configuration space (with opposite pros and cons).
Moreover, up to a few years ago most of the research has been focused on two-point
statistics (P(k) and 2PCF), and only a few efforts have been made on higher-orders
(bispectrum, B(k), and three-point correlation function, 3PCF).
While it is predictable that to maximize the scientific exploitation and accuracy in
cosmological parameter constraint the combination of all these measurements should be
combined in a joint analysis, no attempt has been currently made in this direction. Only
one work explored the combined constraints on 2PCF+P(k) (Sanchez et al. 2016), finding
promising results. Furthermore, recent works have addressed bridging the gap between
Fourier and configuration space higher-order modelling. This has opened the path to a
comprehensive joint likelihood including lower- and higher-order analysis to mitigate
possible systematics and increase the statistical significance of the clustering analysis.
However, in view of the upcoming large spectroscopic surveys that will revolutionize the
field with unprecedented statistics of galaxies, it is crucial to take this step.

Outline of the Project: The aim of this Ph.D. Thesis will be to develop a framework for
the combined analysis of clustering 2-point and 3-point statistics both in configuration
and in Fourier space, namely the 2-point correlation function, the 3-point correlation
function, the power spectrum and the bispectrum. Building on the wide expertise of our
group on clustering analysis (both on 2-point and 3-point correlation functions) and on
the combination of different statistics, the Ph.D. student will base his/her work on the
CosmoBolognaLib libraries (Marulli, Veropalumbo & Moresco, 2016), working to extend
these to provide a comprehensive pipeline for the joint analysis of
2PCF+3PCF+P(k)+B(k).
The work will be divided into the following steps:
1. Development of a pipeline for the analysis of 2PCF + P(k) and 3PCF + B(k), starting
with a focus on the constraints that can be obtained on bias parameters;
2. Assessment of the cross-covariance between the various statistics (exploiting a
theoretical and/or numerical approach);
3. Exploring the constraints that can be obtained on cosmological parameters
expanding the modeling through emulators developed with Machine Learning
algorithms: this will allow us to explore the constraints at the BAO and/or
nonlinear scales;
4. Extend the pipeline for the joint analysis 2PCF+P(k)+3PCF+B(k) analysis;
5. Application of the pipeline to simulated and real data, assessing the gain in
constraining power obtained with the full combination and the relative
contribution of each term, and providing forecasts and new constraints on bias and
cosmological parameters (e.g. exploring Euclid simulation and real data datasets
like eBOSS, DESI and catalogs of cluster of galaxies);
6. Test the new developed pipeline on real Euclid data.

The Ph.D. student will approach and strengthen knowledges in galaxy clustering and
Large Scale Structure, and will be also introduced in Italian and international
collaborations that focus on this field (e.g. Euclid).
This work could provide a fundamental tool not yet explored in view of the large
spectroscopic surveys that are taking data in this moment (like Euclid), and will be
extremely timely to extend the current capabilities in an uncharted but exciting territory.
From this point of view, the developed pipeline will be applied to the state-of-art data that
will be available at the time needed.

Contacts:
prof. Michele Ennio Maria Moresco
Associate professor
Department of Physics and Astronomy – University of Bologna
address: via Gobetti, 93/2, 40129, Bologna
email: michele.moresco@unibo.it - phone: 051/2095775
 PhD project in ASTROPHYSICS

Title of the Project: A multi-wavelength view of galaxy clusters from Euclid and
XMM-Newton

Supervisor: Prof. Lauro Moscardini (DIFA)

Co-Supervisors: Dr. Micol Bolzonella (INAF-OAS)

Scientific Case:
The Euclid telescope is a space mission developed by the European Space Agency (ESA)
with contributions from NASA, aiming at observing 14000 deg2 with grism NIR
spectroscopy and photometry across visual and NIR wavelengths. While its primary goal
is to investigate the mysteries of dark energy and dark matter, Euclid’s observations in 3
deep fields promise a lasting legacy across various aspects of astrophysics, from galaxy
clusters to AGN. Launched on July 1st 2023, Euclid started the survey operations on
February 14th, 2024, marking the beginning of a six-year programme.
XMM-Newton, short for X-ray Multi-Mirror Mission, is an X-ray observatory launched
by the European Space Agency (ESA) in December 1999. It is one of the most powerful X-
ray telescopes ever built, designed to observe high-energy phenomena in the universe
with unprecedented sensitivity and spatial resolution.
Recently, a XMM Multi Years Heritage programme (PI M. Pierre, co-PI M. Bolzonella,
B. Maughan, S. Paltani) has been awarded with 3.5Ms to obtain the coverage of the 10deg2
of the Euclid Deep Field Fornax at 40ks depth.
The Fornax Deep Field will be the deepest among the 3 Euclid Deep Fields; the
concurrent XMM observations promise to deepen our understanding of galaxy clusters,
including a deep characterisation of Euclid-detected clusters and their selection function
and a robust measurement of cluster scaling relations to z = 1.5 and in the galaxy group
regime.
The project will be carried out in the framework of the Euclid collaboration, including
~2000 international scientists. In Bologna (DiFA and INAF institutes) there is a large and
lively research group dealing with many different aspects of the science that will be
enabled by Euclid data.

Outline of the Project:

The project, to be discussed with the PhD candidate, can include some of the following
aspects.
- Characterisation of X-ray and optical properties, their differences to analyse the
systematics affecting the selection at different wavelengths, and comparison with
simulated ones;
- Cross-identification of clusters identified in Euclid and XMM to constrain both the
baryonic and dark matter components;
- Predictions and analysis of the scaling relations (between temperature,
luminosity, richness) to study the feedback and the connection between the
cooling of ICM, fuelling of star formation, accretion of AGN, and presence of
energetic outflows; these feedback processes are fundamental to understand the
 galaxy stellar mass function and are a critical ingredient of cosmological
simulations.

Contacts: Lauro Moscardini (lauro.moscardini@unibo.it), Micol Bolzonella

(micol.bolzonella@inaf.it)
 PhD project in ASTROPHYSICS

Title of the Project:

Detecting Clusters and Voids using Weak Gravitational Lensing

Supervisor: Lauro Moscardini

Co-Supervisors: Carlo Giocoli, Federico Marulli, Giulia Despali

Scientific Case:
Wide-field surveys, such as those conducted by the ESA Euclid mission and LSST-Rubin,
will use weak gravitational lensing as a primary cosmological probe. The slight
distortion of intrinsic galaxy shapes, caused by the intervening matter density
distribution, enables us to trace the growth of structure over cosmic time. The high galaxy
number density and wide sky coverage expected from these two observatories will allow
for unprecedented precision in constraining cosmological parameters. This, in turn,
will open the possibility of using the weak lensing signal to detect and characterise both
dense and underdense regions, such as galaxy clusters and cosmic voids. The accuracy
and precision of these methods require the development of dedicated weak lensing light-
cone simulations to refine techniques and modeling. In particular, cluster and void
lensing are expected to be sensitive to dark energy equation-of-state parameters,
massive neutrinos, and modified gravity. In this PhD thesis, dedicated weak lensing
light-cone simulations will serve as cosmic reference laboratories. The models and results
will then be applied to real photometric weak lensing data.

An example of the weak lensing light-cone simulation constructed from a numerical cosmological simulation.

Outline of the Project:

During the initial phase, the student will focus on constructing dedicated weak lensing
simulations using the tools and data sets available within our group. This will involve
projecting matter density distributions from cosmological numerical simulations and
tracing light rays using the ray-MapSim routine (Giocoli et al. 2015). The resulting shear
and convergence maps will then be used to extract the shear catalogue of sources,
assuming a nominal depth consistent with expectations from the Euclid and LSST-Rubin
telescopes.
Knowing the underlying galaxy cluster population, the student will test the performance
of an optimal filter-based algorithm to identify galaxy clusters (peaks in the weak lensing
convergence and shear maps) using the shear catalogues. The feasibility of the method
has already been demonstrated in a series of works (Pace et al. 2007; Trobbiani et al. 2025
- as a pioneering analysis). The tool needs to be scaled and tested on more accurate and
updated simulations before being applied to real data.
This second activity will give us the possibility to construct a cluster weak lensing
selection function required to complement the photometric one (Sartoris et al. 2016)
and to derive complementary constraints on the main cosmological probes.
As galaxy clusters trace the overdensities of the projected matter density distribution,
cosmic voids delineate the underdensities (valleys in the weak lensing convergence and
shear maps). As a third activity, the student will develop and optimise a new algorithm to
identify and characterise cosmic voids using weak lensing information, paving the
way toward new research topics (Melchior et al. 2012; Sanchéz et al. 2017; Fang et al.
2018).

Noised and smoothed convergence maps considering different choices for the filter scale. The top left panel
displays the original convergence map. Moving from left to right, the other top panels show the convergence
maps with artificial noise added and filtered, using filter sizes of 0.1, 0.5, and 1 arcminute. The bottom sub-
panels display the regions in the corresponding maps that are above the noise level.

The work activities performed during the PhD period will be based on various
international collaborations that our group in Bologna has, framed within different
work packages of the ESA Euclid Collaboration (https://www.euclid-ec.org) and LSST-
Rubin. In this way, the student will have great opportunities to interact with a diverse
group of scientists, gaining the appropriate skills for a fruitful career.

Contacts: lauro.moscardini@unibo.it, carlo.giocoli@inaf.it

 PhD project in ASTROPHYSICS

Title of the Project:

Statistical Tools for Cluster Cosmology Studies in the ESA-Euclid Era Mission

Supervisor: Lauro Moscardini (DIFA)

Co-Supervisors: Carlo Giocoli (INAF-OAS), Federico Marulli (DIFA), Massimo
Meneghetti (INAF-OAS)

Scientific Case:
The successfully launched ESA-Euclid telescope is expected to deliver much data to the
scientific community. Galaxy cluster cosmology is expected to increase the constraining power
to test general relativity further to the
two primary cosmological probes:
galaxy clustering and weak gravitational
lensing. Thanks to the exquisite data we
are already receiving, the developed
processing functions will be able to
measure with extreme precision both the
redshifts and the shapes of the large
number density of photometric galaxies
– approximately 30 galaxies per square
arcminutes. The primary objective will
be to measure the clustering and the
weak lensing to trace the growth of
structures from the present time up to
high redshifts: z⩬2. In addition, the
Galaxy Cluster Science Working Group
has defined the guidelines for using the
photometric galaxy catalog to identify
groups and clusters of galaxies (Sartoris
et al. 2016, Adam et al. 2019) thanks to
two algorithms: AMICO and PZWav. The weak lensing data, associated with the tiny distortion
of the shape of background galaxies lying beyond the clusters, will be of primary importance
in weighting the cluster mass. Using clusters as a cosmological probe, their abundance and their
spatial distributions as a function of redshift, rely on the bias and the accuracy with which we
can measure their mass and combine them with complementary cosmological data.
In recent years, the Bayesian, machine learning, and forward model methods have acquired
great statistical interest in astrophysics and cosmology. Those represent the state-of-the-art
tools that will be used to analyze upcoming data from the approaching wide-field photometric
data.

Outline of the Project:

The student will be fully involved in scientifically exploiting the cluster cosmological studies
within the Euclid Consortium. She/he will join the Consortium, becoming a member of the
Clusters of Galaxies, Strong Lensing, and Weak Lensing Science Working Groups.
The activities will be devoted first to constructing dedicated weak lensing simulations of
clusters extracted from hydrodynamical runs and pseudo-analytical realizations using the
MOKA code (Giocoli et al. 2012). The image below, from Meneghetti et al. (2017), displays
the projected mass density distribution of the cluster mass generated by MOKA (left panel) and
the SkyLens image simulation on the right.

The simulations will be useful for several applications. For example, they will be a valuable
training set to build deep learning models for the statistical inference of several cluster
properties (mass, concentration, triaxiality, etc.) based on the observed lensing signal. In
addition, they will be used to study how deep learning methods compare to more traditional
methods for measuring the same properties (for example, by fitting projected shear profiles).
Furthermore, their analysis will inform us of mass biases depending on other cluster properties.
An interesting extension of the lensing simulations could be deriving additional simulated
observables for the same clusters (e.g., X-ray emission, SZ signal, optical and near-infrared
imaging, etc). Such complementary data would allow us to investigate the impact of possible
selection effects on the measurement of cluster structural properties. Thus, by developing the
simulated dataset, the student will acquire know-how on weak lensing, multi-wavelength
observations, and fast statistical methods.
In a second step, he/she will then improve and optimize the cosmological pipeline starting from
the cluster catalogs of the Euclid Collaboration (EC) and develop a mathematical forward
model to derive cosmological parameters and combine them with the corresponding clustering
and weak lensing constraints (To, Krause et al. 2021). The CLOE pipeline already developed
within the EC, together with the results from the first part of the project, will represent the
starting point for this section. The student will also be involved in studying and modeling the
group and cluster weak lensing profiles using the developed statistical methods and benchmark
possible dependencies on cosmology.
The framework of this Ph.D. project within an international scientific community will allow
the student to improve his/her expertise, learn new methods, and possibly construct networking
for a successful future in science research. A 3-6 month visit for scientific collaboration in one
of the international institutions involved in the collaboration will be planned during the Ph.D.
period.

Contacts: Lauro Moscardini (lauro.moscardini@unibo.it), Carlo Giocoli

(carlo.giocoli@inaf.it), Federico Marulli (federico.marulli3@unibo.it), Massimo
Meneghetti (massimo.meneghetti@inaf.it)
 PhD project in ASTROPHYSICS

Title of the Project:

Implementing new physics in the modeling of the stellar atmospheres

Supervisor : A. Mucciarelli (DIFA)

Scientific Case:
A model atmosphere is a numerical model that describes the physical state of the plasma in the outer
layers of a star, and is used to compute observable quantities, such as the emerging spectrum or colours.
The level of realism in the physical treatment of these models has a fundamental impact on the chemical
abundances derived from spectra, as well as on the photometric colors or the integrated spectra predicted
for complex populations such as galaxies. All the model atmospheres widely adopted are based on the
assumptions of local termodynamical equilibrium and one dimensional geometry. These assumptions
are not always valid leading to significant variations in the chemical abundances that we derive.

Outline of the Project:

The goal of the project is to implement new physical processes in public computational codes for model
atmosphere and spectral synthesis. Several physical processes need to be introduced or updated in the
calculation of both the atmosphere model and the emerging flux, for instance: (1) an appropriate
treatment of the non local thermodynamical equilibrium in spectral synthesis, (2) the impact of three-
dimensional geometry on the model atmospheres, (3) updated physics for collisional broadening in the
calculation of the line profile, (4) the impact of non standard chemical mixtures in classical one
dimensional models.
The candidate will have the opportunity to develop various aspects of the project, interacting with
astronomers from other European institutions who are experts in NLTE and 3D models atmospheres.

Contacts:
alessio.mucciarelli2@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project:

Evolution of CNOPS elements in the Milky Way

Supervisor : A. Mucciarelli (DIFA)

Co-Supervisor : D. Romano (INAF-OAS)

Scientific Case:
Carbon, nitrogen, oxygen, phosphorus, and sulphur (hereinafter the CNOPS elements) are the
building blocks of all life on Earth. Understanding their formation in stars and evolution in the
Milky Way is a fundamental step to the definition of the “Galactic Habitable Zone” and its
evolution in time and space in the Galaxy.
This PhD project is part of the international collaboration SPONGE (Sulphur, Phosphorus,
Oxygen, Nitrogen and carbon Galactic Evolution) that aims to address the fuzziest aspects
of CNOPS evolution by means of both novel spectroscopic observations and cutting-edge
galaxy formation and evolution models.

Outline of the Project:

The PhD candidate shall reduce, analyze, and provide theoretical interpretations of proprietary
data already in hand, while also being involved in the preparation of next observational
campaigns by the team. Indeed, within SPONGE we are obtaining high-resolution stellar
spectra to measure the C and O isotopic ratios (12C/13C, 16O/18O) of unevolved stars - the
sole that can effectively constrain Galactic chemical evolution models, because their
atmospheric abundances are unaffected by mixing processes typical of later stellar evolutionary
phases. It is worth noticing that none of past, current, or planned large spectroscopic surveys
can provide such data, so our effort nicely complements that of the community.
Moreover, the student will have access to complementary molecular cloud data (12C/13C,
14N/15N, 16O/17O, 16O/18O, 32S/33S, 32S/34S) obtained in the framework of several
international collaborations, which will allow him/her to study the variation of the isotopic
ratios not only in time in the solar neighborhood, but also across the Milky Way disc at the
current time. All of this, jointly to the availability of a proprietary Galactic chemical evolution
code that is maintained and constantly upgraded in Bologna, will put him/her in the prime
position of being able to obtain and interpret unique data, with an assured large impact on the
community.

Contacts:
alessio.mucciarelli2@unibo.it
donatella.romano@inaf.it
 PhD project in ASTROPHYSICS

Title of the Project:

Reconstructing the mass assembly history of the Milky Way

Supervisor : A. Mucciarelli (DIFA)

Co-Supervisor : D. Massari (INAF-OAS)

Scientific Case:
The exquisitely precise proper motions and parallaxes provided by the ESA-Gaia space mission
are revolutionising our view of the structure and evolution of the Milky Way (MW). In particular,
in the lapse of just few years, our understanding of the stellar halo in the surroundings of the Sun
has completely changed.
The commonly accepted scenario predicts that a significant portion of the retrograde halo (RH)
was created as a result of a merging event between the MW and an ancient relatively massive
dwarf galaxy, known as Gaia-Enceladus. Further analyses revealed additional substructures in the
RH and led to the conclusion that the RH component could be entirely, or at least for the most part,
made up of accreted star. However, the investigation of these sub-structures composing our Halo
is still is its infancy and a complete characterization of stars belonging to former satellites needs
the combinations of kinematical and chemical properties of individual stars.

Outline of the Project:

The PhD project is aimed at describing the chemistry of Milky Way stars belonging to sub-structures
identified accoridng to their kienmatical properties. In fact, the chemical abundance patterns of
individual stars carries distinct signatures of the formation process and chemical enrichment histories of
each past merger progenitor, and thus crucially helps in differentiate between dwarf galaxies with
different mass and star formation efficiency.
The project will benefit from proprietary and archival high-resolution spectra obtained with ground-
based telescopes (i.e. VLT, LBT,Subaru,Keck) that will be analysed, together with kinematic data from
the Gaia mission, to derive a complete screening of stars in the RH and likely accreted from now
dissolved MW satellites.

Foreseen milestones and deliverables

- at least one refereed paper per year in the best impact-factor astronomical journals.
- dissemination of the project results at international astronomical conferences.
- collaboration with world-renowned experts in spectroscopy of resolved stellar populations and in
Galactic archaeology

Contacts:
alessio.mucciarelli2@unibo.it
davide.massari@inaf.it
 PhD project in ASTROPHYSICS

Title of the Project:

Chemical characterization of the Local Group: identifying the chemical DNA of Milky Way
satellite galaxies

Supervisor : A. Mucciarelli (DIFA)

Co-Supervisor : D. Massari (INAF-OAS)

Scientific Case:
According to the Λ cold dark matter cosmological paradigm, structure formation proceeds bottom-up,
as small structures merge to build up the larger galaxies we observe today. The Milky Way is a prime
example of this formation mechanism, as first demonstrated by the discovery of the Sagittarius dwarf
spheroidal galaxy in the process of disruption (Ibata et al.1994), then by halo stellar streams crossing
the solar neighborhood (Helmi et al. 1999), and more recently by the discovery of stellar debris from
Gaia-Enceladus, revealing the last significant merger experienced by our Galaxy (Helmi et al. 2018).
As a result of such merger events, not only stars, but also globular clusters were accreted.
The chemical composition of stars is a powerful tool to reconstruct the history of the parent galaxies
and their possible merger events. In fact, the amount of different metals in a star acts as a powerful
“DNA probe” that allows us to trace the genealogy of each star and to distinguish those formed in other
galaxies and only later added to the main building. This approach has been recently used to identify for
the first time the relic of a past merger event occurring in the Large Magellanic Cloud (Mucciarelli et
al. 2021, Nature Astronomy).

Outline of the Project:

The PhD project is aimed at describing the chemistry of Milky Way satellites (like the Sagittarius dwarf
galaxies, the Large and Small Magellanic Clouds), nearby isolated dwarf galaxies and ultra-faint dwarf
galaxies. The chemical DNA of these galaxies will be compared with that of the Milky Way in order to
reconstruct the chemical enrichment history of these galaxies. Two key questions will be addressed in
this project,

• Assembly history of the massive satellites - the chemistry of field and globular cluster stars of
the most massive Milky Way satellites (i.e. the Magellanic Clouds) will be used to reveal
possible past merger events occurring in their history and to search for the missing satellites of
these galaxies, predicted by Λ cold dark matter simulations. The search for past merger events
in these galaxies is an exciting hot topic in modern astrophysics that is taking its first steps, only
one merger event has been discovered so far in these galaxies (Mucciarelli et al. 2021).
• The early evolution of the interacting satellites – the chemical properties of long-lived, metal-
poor, old stars provide detailed insights into the early ages of these galaxies when they evolved
in isolation and before they start to interact each other. These rare stars will allow us to
understand the impact of first supernovae in different galactic environments and enhance our
comprehension of the first Gyr of life in these systems.

The project will benefit from proprietary and archival high-resolution spectra obtained with ground-
based telescopes (i.e. VLT, LBT,Subaru,Keck) that will be analysed to derive a complete screening of
the chemical properties of these stars (see Minelli et al. 2021a,b for some examples of the adopted
approach).
Foreseen milestones and deliverables
- at least one refereed paper per year in the best impact-factor astronomical journals.
- dissemination of the project results at international astronomical conferences.
- collaboration with world-renowned experts in spectroscopy of resolved stellar populations

Contacts:
alessio.mucciarelli2@unibo.it
davide.massari@inaf.it
 PhD project in ASTROPHYSICS

Title of the Project: Local gravitational instability of stratified rotating fluids

Supervisor: Carlo Nipoti (UniBo)

Scientific Case:
Fragmentation of rotating gas systems via gravitational instability is a crucial mechanism
in several astrophysical processes, such as formation of planets in protoplanetary discs
and of star clusters in galactic discs. Gravitational instability is fairly well understood for
infinitesimally thin discs, but the thin-disc approximation is often not justified. Nipoti
(2023) presented new 3D instability and stability criteria, which can be used to determine
whether and where a rotating system of given 3D structure is prone to clump formation.
For a vertically stratified gas disc of thickness h_z, the instability criterion takes the form
Q_3D<1, where Q_3D, depending on h_z and on the local gas properties, is a 3D analogue
of the classical 2D Toomre (1964) Q parameter. The Q_3D criterion has been recently
applied to observed galactic gaseous discs by Bacchini et al. (2024), and extended to
multicomponent discs by Nipoti et al. (2024).

Outline of the Project:

The PhD student will study the local gravitational stability properties both of observed
systems and of models. As far as observed systems are concerned, the student will extend
the study of Bacchini et al. (2024) by considering the 3D stability and instability criteria
to thick multi-component discs for which we have information on the vertical structure,
ranging from protoplanetary discs to gaseous galactic discs at low and high redshift.
As far as models are concerned, the student will build numerical (as in Nipoti and Binney
2005) and analytic (as in Sotira 2022) equilibrium models of self-gravitating rotating
fluids and will apply to these models the 3D gravitational stability criteria. The analytic
results will be complemented by numerical hydrodynamic simulations aimed at studying
the non-linear behaviour of the models.

Contacts: carlo.nipoti@unibo.it

References:

• Bacchini C., Nipoti C., et al., 2024, A&A, 687, A115

• Nipoti C., 2023, MNRAS, 518, 5154
• Nipoti C., Binney J., 2015, MNRAS, 446, 1820
• Nipoti C., Caprioglio C., Bacchini C., 2024, A&A, 689, A61
• Sotira, S., 2022, "Analytic models of self-gravitating rotating gaseous tori with
central black hole", Master Thesis, University of Bologna
• Toomre A., 1964, ApJ, 139, 1217

Bologna, 21/3/2025
 PhD project in ASTROPHYSICS

Title of the Project:

Simulations of the collisional evolution of globular clusters with Monte Carlo methods

Supervisor: Carlo Nipoti (UniBo)

Co-supervisor: Raffaele Pascale (INAF-OAS)

Scientific Case:
Globular clusters are the perfect environment to study the evolution of stellar systems
over timescales where the effects of collisionality on their dynamics cannot be neglected.
Indeed, globular clusters are dynamically old, dense agglomerates of stars with relaxation
time (i.e. the time needed by the stars to redistribute efficiently their energy due to two
body encounters) way shorter than the age of the Universe, which makes them susceptible
to processes of energy equipartition, mass segregation and gravitational evaporation. In
this context, Monte Carlo (Henon 1971) algorithms are a special family of methods,
alternative to and less computational expensive than N-body simulations, suited to follow
the long time, dynamical evolution of stellar systems once the integrals of motion of their
tracers are perturbed to account for two-body interactions.

Outline of the Project:

The PhD student will develop a novel version of the orbit-averaged based Monte Carlo
method presented in Sollima and Mastrobuono Battisti (2014), optimized to model
spherical stellar systems as globular clusters with the inclusion of binaries, stellar
evolution and external tidal force fields (e.g. Sollima and Ferraro 2019,). The code, first
developed in Fortran77, will be partially ported in Python and complemented by flexible
tools to handle the statistical and graphical analysis of typical outputs of the codes, as well
as new features to account in the models for central intermediate massive black holes, a
continuous mass spectrum in the initial distribution of stars, and more general initial
conditions. From the model it is possible to compute observables to te directly compared
with observations of real globular clusters. The software will be then used to model the
dynamical evolution of a set of globular clusters orbiting around the Milky Way to study
mass segregation and the effect of massive dark remnants (e.g. black holes) at the center
of the system.

Contacts: carlo.nipoti@unibo.it , raffaele.pascale@inaf.it

References:
• Henon M.H., 1971, ApSS, 14, 151
• Sollima A., Mastrobuono Battisti A., 2014, MNRAS 443, 351
• Sollima A., Ferraro F.R., 2019, MNRAS, 483, 1523

Bologna, 21/3/2025
 PhD project in ASTROPHYSICS

Title of the Project: Global stability of stellar discs with dark matter halos

Supervisors: Carlo Nipoti (UniBo), Luca Ciotti (UniBo), Silvia Pellegrini (UniBo)

Scientific Case:
Thin stellar discs are prone to global instability and bar formation. The formation and evolution of the
bar is an open research field, addressed by means of N-body simulations since the early 1970s (e.g.
Ostriker and Peebles, 1973). Some criteria have been studied to understand the conditions for the
development of global instabilities in the stellar disc leading to bar formation. The most common
global stability parameter, due to Ostriker and Peebles (1973), is t=T/|U|, where T is the ordered
kinetic energy of the system and U is the total gravitational energy. An alternative global stability
parameter has been proposed by Efstathiou et al. (1982): t*=T*/|W*|, where now T* is by definition
the stellar order kinetic energy and W* is the trace of the gravitational interaction energy tensor of the
stars in the total gravitational potential.
Whether either of these parameters is sufficient to describe the global stability of stellar discs in the
presence of dark matter halos is still debated.

Outline of the Project:

In this project, the student will study the global stability of stellar discs in the presence of dark matter
halos, using high-resolution N-body simulations. Following the approach of the preliminary
explorations of Caravita (2022) and Cantarella (2023), the student will construct N-body realizations
of equilibrium two-component galaxies, with stellar disc and dark matter halos. The considered
systems will differ greatly ranging from simpler cases of thin discs with “frozen” dark matter halos to
more realistic cases of thick discs with “live” dark matter halos, for which a careful study of the
distribution functions will be necessary. The stability of these systems will be studied by following
their evolution with N-body simulations. The results of the simulations, combined with the
measurement of the parameters t and t* of the initial conditions, will allow to draw conclusions on the
proposed stability criteria and possibly also to construct new stability criteria.

Contacts: carlo.nipoti@unibo.it , luca.ciotti@unibo.it, silvia.pellegrini@unibo.it

References:
- Ostriker, J. P. and Peebles, P. J. E., 1973, ApJ, 467-480
- Efstathiou, G., Lake, G. and Negroponte, J., 1982, MNRAS, 199, 1069-1088
- Caravita, C., 2022, PhD thesis, University of Bologna
- Cantarella S., 2023, Master thesis, University of Bologna

Bologna, 21/3/2025
 PhD project in ASTROPHYSICS

Title of the Project: Probing black holes through gravitational wave and quantum
signatures

Supervisor: Carlo Nipoti (UniBo)

Co-supervisor: Roberto Casadio (UniBo)

Scientific Case:
The detection of gravitational waves (GWs) by the LIGO/Virgo/KAGRA collaboration has
revolutionized our understanding of the Universe, providing direct insights into the
population of compact objects, and in particular stellar mass black holes (BHs). The future
GW detectors Einstein Telescope, Cosmic Explorer, and LISA, in synergy with pulsar
timing array experiments such as that of the NANOGrav Collaboration, will significantly
enhance our ability to detect GWs also from other categories of BHs, such as the
supermassive BHs (SMBHs) that seem ubiquitous in massive galaxies, the more elusive
intermediate mass BHs (IMBHs) and the exotic population of primordial black holes
(PBHs). Depending on the formation scenario, PBHs can cover several orders of
magnitude in mass, accounting for possible dark matter particles, and seeds for high
redshift SMBHs. Gravitational signatures associated with PBHs formation and evolution
can significantly vary, contributing to the cosmic gravitational wave background, together
with other sources such as IMBH and SMBH binaries.

Outline of the Project:

The aim of this project is to improve our understanding of some properties of different
categories of BHs. For SMBHs we can explore the possibility of using observational
constraints on the redshift-dependent galaxy properties and merging hierarchy to
sharpen the predictions of low-frequency GW from SMBH binaries (see Ellis et al. 2024).
For GWs from IMBH binaries we can investigate models with realistic and redshift-
dependent properties of the hosts, which are expected to be globular clusters (or their
progenitors) and dwarf galaxies (see Khan et al. 2024). For PBHs one can consider
quantum corrections observable in GW signals, focusing on induced GWs (generated at
second order by curvature perturbations) or on high-frequency GWs from Hawking
evaporation (see Dong et al. 2016 and Franciolini et al. 2023).

Contacts: carlo.nipoti@unibo.it , roberto.casadio3@unibo.it

References:

• Dong, R. et al., 2016, JCAP, 10, 034

• Ellis, J. et al., 2024, Phys. Rev. D, 109, 2, L021302
• Franciolini, G. et al 2023, Phys. Rev. D, 108, 4, 043506
• Khan, F. et al. 2024, ApJ, 976, 1

Bologna, 21/3/2025
 PhD project in ASTROPHYSICS

Title of the Project: Hydrodynamic simulations of Terzan 5 and bulge fossil fragments

Supervisor: Carlo Nipoti (UniBo)

Co-supervisors: Francesco Calura (INAF-OAS), Francesco Ferraro (UniBo)

Scientific Case
Understanding the origin of globular clusters (GCs) and their multiple stellar populations
is a major challenge in modern astronomy. Peculiar cases are represented by the so-called
bulge fossil fragments (BFFs) Terzan 5 and Liller 1 that, at variance with ordinary GCs,
display multiple sub-populations of stars with large differences in age and in iron
content. The complex abundance pattern of these systems indicates an enrichment
history characterized by multiple star formation episodes, separated by time intervals as
long as a few Gyrs. This non-trivial feature is unexpected for a GC and various
explanations have been proposed: besides the possibility that they are remnants of long-
lived clumps, most of which eventually merged to form the Bulge, they may also be
accreted nuclear star clusters formed in dwarf galaxies (Bastian & Pfeffer 2022) or the
result of existing GCs accreting gas and forming a new stellar generation. The aim of the
present project is to investigate the latter possibility.

Outline of the Project

To explain the formation of the complex stellar populations of Terzan 5 and its analogues,
we propose to use three-dimensional hydrodynamic simulations and model the
encounter of an old stellar population with a reservoir of cold gas, such as a molecular
cloud.
We propose to use a customized version of the RAMSES code (Teyssier 2002) which
includes basic yet realistic physical ingredients, such as radiative cooling, star formation,
feedback and chemical enrichment (Lacchin et al. 2021; Calura et al. 2022).
The results of the simulations will be compared with the observational properties of these
systems, including their abundance pattern and colour-magnitude diagrams, in an effort
to make significant progress in our understanding of the complex history of the BFFs.

Contacts: carlo.nipoti@unibo.it , francesco.calura@inaf.it, francesco.ferraro3@unibo.it

References:
- Bastian N., Pfeffer J., 2022, MNRAS, 509, 614
- Calura F., Lupi A., Rosdahl J., Vanzella E., Meneghetti M., Rosati P., Vesperini E., et
al., 2022, MNRAS, 516, 5914
- Lacchin E., Calura F., Vesperini E., 2021, MNRAS, 506, 595
- Teyssier R., 2002, A&A, 385, 337

Bologna, 21/3/2025
Title of the Project: Exploring binary millisecond pulsars in globular clusters through
optical/near-infrared observations.

Supervisor: C. Pallanca
Co-Supervisors: M.Cadelano, F.R. Ferraro, B. Lanzoni

Scientific Case:
Globular clusters (GCs) are old, compact and dense gravitationally bounded stellar systems. They
are collisional systems and are the main efficient factories of peculiar stellar populations, as
millisecond pulsars (MSPs). In fact, the number of MSPs per unit mass in the Galactic GC population
is significantly larger than in the Galactic field. MSPs are stable and fast rotating neutron stars,
emitting a collimated radio periodic signal (e.g. usually described with the “lighthouse” model) with
typical periods of milliseconds. The main formation scenario of these object is commonly known as
the “recycling scenario”, according to which a NS is spun up by mass accretion in a binary system.
In this context MSPs companions are expected to be He-white dwarfs (WD, i.e. the residual cores
of the peeled companions that recycled the pulsars). However, even if several He-WD companions
have been already identified as companions to MSPs, a zoo of unique objects is emerging. This is
not surprising considering the host environment. Indeed, the active innermost regions of GCs may
perturb the canonical evolution of these binary systems.

Outline of the Project:

The unprecedented power of recent radio telescopes (e. g. MeerKAT and FAST) is propelling MSPs
detection into a thriving era. Taking advantage of this significant improvement, the Galactic globular
cluster MSP population has increased by >80% in the last years. Therefore, the time is ripe for a
thorough study of companions to binary MSPs in GCs. A photometric search for companions to
binary MSPs hosted in GCs will be performed. For each target, the astrometric position, the CMD
location and the presence of variability will be investigated. To achieve these goals, multi-filter and
multi-exposure data-set at high spatial resolution, such as proprietary and archival JWST and HST
observations, will be used. The optical identification of the companion stars to MSPs will bring key
information on the nature, the physical parameters, the evolutionary processes and the recycling
mechanisms occurring in these systems. Secondly, the full characterization, in synergy with radio
and X-ray studies, of binary MSPs will enable a wealth of groundbreaking scientific applications,
such as testing general relativity and alternative theories of gravity, studying stellar and binary
evolution and constraining the equation of state of matter at the nuclear equilibrium density, thus
eventually opening a new window in the domain of Fundamental Physics research. Finally, linking
the current properties of the MSP population to the internal dynamical status of the host cluster, will
clarify the role that the most massive objects/binaries play in the evolution of GCs, and, vice versa,
the role that internal dynamical processes play in the evolutionary path of these objects. Such a
project will set the stage of our understanding of the population of MSPs.

Main external Collaborators: Emanuele Dalessandro (OAS-Bo), Paulo Freire (Max Planck
Institute, Germany), Craig Heinke (Alberta University, Canada), Scott Ransom (NRAO, USA),
Alessandro Ridolfi (Bielefeld University, Germany)

Contacts: cristina.pallanca3@unibo.it

Viale Berti Pichat 6/2 - 40127 Bologna - Italia - Tel. +39 051 2095162
Via Irnerio 46 - 40126 Bologna - Italia - Tel. +39 051 2091004
Via Gobetti 93/2 - 40129 Bologna - Italia - Tel. +39 051 2095701
difa.direzione@unibo.it - difa.dipartimento@pec.unibo.it
https://fisica-astronomia.unibo.it/it
 PhD project in ASTROPHYSICS
PhD project in ASTROPHYSICS
Title of the Project:

Title ofand
Formation the evolution
Project: AofBig Model
solar foranalogs:
system Big Data:gravitational
Forward Modeling the Colors of
Millions of Galaxies
interaction with planets and/or external perturbers

Supervisor
Supervisor : SirioRoccatagliata
: Veronica Belli
Co-Supervisors : Lucia Pozzetti
Scientific Case: Solar system analogs host a remnant of the protoplanetary disks around the
Scienti>ic
central star, the Case: Recent
so-called debrisobservations
disks. Thesewith are the James
formed Webb
as a Space of
by-product Telescope (JWST) have
planet formation
discovered
and consist a population
of planetary remnants ofsuch
massive galaxies
as dust, gas, andthat are already
planetesimal “redDue
belts. andto dead” (i.e., have
dust's short
stopped
lifespan, formingcontinuous
it requires new stars)replenishment
at redshift z >through
4, whenplanetesimal
the universecollisions.
was still young
Moreover,and rich
substellar companions can significantly influence dust and planetesimal dynamics
in gas. This discovery opens up fundamental questions about the population of quiescent through
gravitational
galaxies:effects.
whenEven smallKirst
did they planets
form?canWhat
leavephysical
distinctive marks onare
processes debris disk structures,
responsible for turning
while misaligned planets or those with elliptical orbits may reveal past gravitational interactions,
off their star formation in the early universe? What is the role played by mergers in
also during a flyby. N-body simulations, SPH simulations, and collisional evolution models of
shaping the properties of galaxies? So far, the study of the most massive, and therefore
debris disks predicted peculiar substructures induced by planet-disk interaction which might be
rare, galaxies
potentially at high
observable. redshift
Flybys has been
can also limited by the
be responsible of alack of both wide
perturbation anddynamical
of the deep surveys.
Luckily,in athe
interaction newdebris
generation of observatories
disk system. However, are rapidly
recent providingsuggest
observations enormous the amounts
close of
data that
encounters cancan be used to study
be fundamental even forallthe
types of galaxies,
formation including
of the debris disk the ones themselves.
systems belonging to rare
populations. Space missions are Kinally mapping the universe in the near-infrared, which
is crucial
Outline of the for the study
Project: of distant
The student will galaxies:
first collectJWST has already
a sample of debrisobserved more than
disks highlighting thehalf a
million galaxies between the local universe and the epoch of reionization; and Euclid is
resolved ones at different wavelengths, and those with planets.
currently
A coherent observing about
characterization of theastellar
million galaxiesofevery
properties singlestar
the central day.hosting
Space-based infrared
the debris disks data
will be obtained by the student in clusters and isolated objects. This
will be complemented by optical observations from ground-based facilities such will be done viaas the
spectroscopic
Vera Rubinanalysis and/or via
Observatory, spectral
which willenergy distribution.
start science Timescale
operations of collisions in debris
soon.
disks will be here constrained when multi-epoch observations of the far-infrared excess are
available.
Outline of the Project: The student will analyze galaxy photometry using observations
Next, the student will develop a comprehensive analysis of the Gaia DR3 (and eventually DR4)
from JWST
astrometric data to (atreconstruct
high redshift), Euclid
the flyby and Rubinby(at
experienced low
the to intermediate
system redshift).
during its life. This willThe
be Kirst
donestep will abelinear
first with the measurement
approximation to ofstatistically
number densities
constrainfor
thedifferent
frequency galaxy populations
of at least one close
flyby.selected on the basis of their physical and observational properties (such as mass,
redshift,
According to theand colors).
attitude Next,
of the the student
student willwill
the project develop
proceed a comprehensive
in different ways.empirical model
One possibility
is thewith a small
proper number
dynamical of free parameters
reconstruction that is able
of the multiple flybystowith
reproduce, for each
the relative orbit bin in mass
deviation.
andpossibility
Another redshift,isthe thenumber
reduction density
of new of galaxies with
high-contrast different
imaging colors, thus
observations capturing
(already the
available)
of thediversity
debris diskof galaxies from quiescent (red) to star-forming (blue), including all the of
systems. The student will then led new proposal on a particular sample
debrisintermediate
disks. stages. Finally, the empirical model will be evolved forward in time,
The student
accounting will beforpart
theof the important
most Bologna-based and will
physical also work ingas
mechanisms: collaboration with national
inKlows, galaxy mergers,
and international network of colleagues.
stellar evolution, star-formation quenching, etc. The effect of these processes on the
colors of galaxies will be derived from theoretical studies and numerical simulations.
Finally, using state-of-the-art statistical and computational methods, the evolved model
Contacts: Veronica Roccatagliata (veroni.roccatagliata@unibo.it)
will be Kit to observations at different redshifts, resulting in a comprehensive picture of
the processes driving galaxy evolution, with an emphasis on the formation and evolution
of quiescent galaxies.
 A&A proofs:

PhD project in ASTROPHYSICS

PhD project in ASTROPHYSICS
Title of the Project:

Formation
Title of planets
of the Project: in protoplanetary
A Big Model for Bigdisks
Data: Forward Modeling the Colors of
Millions of Galaxies
Supervisor : Veronica Roccatagliata
Supervisor : Sirio Belli
Scientific Case: High angular resolution observations of dust
Co-Supervisors
continuum at millimeter : Lucia Pozzetti(with ALMA) and high
wavelengths
contrast imaging observations of scattered light in the near-
Scienti>ic
infrared obtainedCase: Recent observations
spectacular observationsofwith the James disks,
protoplanetary Webb
Fig. 6.Space
Left panel: Telescope
Band 4revealing
observations bythe presence
Cazzoletti
(JWST)
Zoom of Figure 1 with have
highlighted
et al. (2018).of
the candidate
Right panel: The co
discoveredin athe
sub-structures population
dust andofgas massive galaxies
distribution, suchthatasare already
lightdust
inner “red
green contour andand
represents
cavities dead”
our Lp-band (i.e., have
observations.
ring-like The central

stopped
structures, forming
vortices and new stars)
spirals. at redshift
Several z > 4, have
mechanisms whenbeenthe universe
proposed was still young
to explain the origin and rich
in gas.
of such This discovery
sub-structures suchopens up fundamental
as: dynamical questions
interaction betweenaboutthe the diskpopulation
and protoplanets; of quiescent
galaxies: when
magneto-rotational did theycondensation
instability, Kirst form? What
fronts physical processes are responsible for turning
or photoevaporation.
Confirmed evidence of two young protoplanets have
off their star formation in the early universe? What is thebeen obtained so far roleonlyplayed
in the dust cavity
by mergers in
of theshaping
disk around PDS 70.
the properties of galaxies? So far, the study of the most massive, and therefore
A new instrument at the VLT, ERIS, provides a unique opportunity to study these structures at high
rare, galaxies at high redshift has been limited by the lack of both wide and deep surveys.
angular resolution using coronagraphic imaging. As member of the INAF/GTO team, we are
Luckily, a new generation of observatories are rapidly providing enormous amounts of
conducting a large program to look for thermal emission from protoplanets in structured protoplanetary
disks data that can
at different be of
stages used
theirto study all
evolution. types
Data of galaxies,
obtained including
in open time are also the ones belonging to rare
available.
populations. Space missions are Kinally mapping the universe in the near-infrared, which
is crucial
Outline for the study
of the Project: In the of
firstdistant galaxies:
step, the student JWST has already
will analyze coronographic observed more thanofhalf a
observations
AS 209million galaxies between the local universe and the epoch of reionization; andPlate
obtained with two different coronographs of ERIS, the vector Apodizing Phase Euclid is
(vAPP) and the observing
currently annular groove about phase mask galaxies
a million (VORTEX) coronagraphs.
every singleFig.day. This will allow ainfrared
Space-based training data
7. Schematic cartoon of the HD 135344B system with position
of the student in the calibration and reduction of the data, using the available
the protoplanet candidate. Gray pipeline and the position of t
regions highlight
will be complemented by optical observations from ground-based ring and asymmetry features facilities
detected by suchALMA, as the
comparing data obtained with broad and narrow band filters. The data post processing will and the solid lin
Vera Rubin Observatory, which will start science operations soon. represent the spiral’s location resolved in the near-/min-infrared.
proceed with different techniques as, the angular differential imaging (ADI) and the annular
principal component analysis (PCA) based algorithm which emphasizes theA.Z.
(project ID 855130). non axisymmetric
acknowledges support from ANID – Millennium S
Outline of the Project: The student will analyze
structures in the disk, as well as point like sources. Other sophisticated galaxy photometry
ence Initiative Program – using
out thanks topost-processing
Center Codeobservations
NCN2024_001. The project was carr
the contribution of Fondazionewill Cassa dibeRisparmio di Firenze,
explored by the student, with the possibility of visiting the developers of those techniques. The Kirst
from JWST (at high redshift), Euclid and Rubin (at low to intermediate
part of the "Ricercatori a Firenze redshift).
2023" grant. The
step
student willwill
havebethe
thepossibility
measurement to go to ofParanal
numbertodensities
perform the forobservations
different galaxy planned populations
in the next
years.selected
The studenton thewillbasis of their
be hence physical few
responsible andsystems,
observational
combiningproperties
References the results (such as mass,
obtained with
ERISredshift, and colors). Next, the student will develop a comprehensive
with the resolved substructures resolved in the disk at different wavelengths.
Alexander, R. D., Clarke, C.empirical model
J., & The
Pringle, student
J. E. 2006, MNRAS, 369, 229
Bae, J. & Zhu, Z. 2018a, ApJ, 859, 118
with
will also beaencouraged
small number of freenew
in leading parameters
proposalsthat on aisparticular
able to reproduce,
sample
Bae, J. & Zhu,of forApJ,
disks.
Z. 2018b, each
859, 119bin in mass
Bae, J., Zhu, Z., & Hartmann, L. 2016, ApJ, 819, 134
This and
thesis will make the student one of the few
redshift, the number density of galaxies with different experts around the
Bonse,colors,
world
M. J., Garvin,thus
on high-contrast
capturing
E. O., Gebhard, theAstronomical Journ
T. D., et al. 2023,
imaging. This expertise will be particularly important also
diversity of galaxies from quiescent (red) to star-formingBoss, for the new instruments
166, 71
(blue), including
A. P. 1997, Science,
on ELT,
276, 1836 all the
where
both, APP and VORTEX coronographs will be mounted e.g. on METIS and
Casassus, S., MICADO.
Christiaens, V., Cárcamo, M., et al. 2021, MNRAS, 507, 3789
intermediate stages. Finally, the empirical model will be Cazzoletti, evolved P., vanforward in time,
Dishoeck, E. F., Pinilla, P., et al. 2018, A&A, 619, A161
The student will be part of the Bologna-based and will also workChristiaens, in collaboration withR., etnational
accounting for the most important physical mechanisms: gas inKlows, galaxy
V., Gonzalez, C., Farkas,
Software, 8, 4774 mergers,
al. 2023, The Journal of Open Sou
and international network of colleagues.
stellar evolution, star-formation quenching, etc. The effect ofG.,these
Cugno, Pearce, T.processes
D., Launhardt, R., eton theAstronomy and Ast
Cugno, G., Leisenring, J., Wagner, K. R., et al. 2024, AJ, 167, 182
al. 2023,
colors of galaxies will be derived from theoretical studies and numerical simulations.
physics, 669, A145

Finally, Veronica
Contacts: using state-of-the-art
Roccatagliata statistical and computational
(veroni.roccatagliata@unibo.it) methods, the evolved model
Article number, page 6 of 10

will be Kit to observations at different redshifts, resulting in a comprehensive picture of

the processes driving galaxy evolution, with an emphasis on the formation and evolution
of quiescent galaxies.
 PhD project in ASTROPHYSICS

Title of the Project: Exploiting the Euclid Legacy for galaxy evolution with ELSA

Supervisor : Margherita Talia <margherita.talia2@unibo.it>

Collaborators : ELSA team members

Scientific Case:
Euclid is an ESA space telescope launched in July 2023, designed to understand the nature of dark
energy and dark matter. To achieve this, Euclid is observing over a third of the sky with high
resolution imaging and spectroscopy, which will establish “the” reference map of the extra-galactic
celestial sphere for decades to come. The giant archive produced will be a goldmine to study the
history of the formation and growth of galaxies over the age of the Universe, driving answers to
many fundamental science questions on the co-evolution of galaxies and supermassive black holes,
the interaction between stars, gas, and galactic nuclei in galaxies at cosmic noon, and excelling in
the discovery of rare objects including gravitational lenses.

Outline of the Project:

The main objective of this project will be the update/development of existing/new tools for
spectro-photometric analysis (i.e. combining both spectroscopic and photometric data) and their
application to Euclid data from the first and second data releases (DR1-DR2) in order to extract a
wide range of physical parameters, including star formation history, dust emission, and metallicity,
providing a complete understanding of the physical and chemical properties of the galaxies
observed by Euclid.
The project will consist of the following main steps:
1) Do a complete census of existing spectro-photometric codes, to be tested and adapted to
Euclid data using custom simulated photometric catalogues and spectra. If needed, develop
a new tool for spectro-photometric analysis specifically tailored to the analysis of very large
datasets. The application of machine learning algorithms will also be explored.
2) Test the feasibility of spectro-photometric analysis on individual galaxies and select a
suitable sample from the Euclid dataset. Build stacked datasets using the codes already
developed at DiFA (Quai et al., in preparation) in order to extend the analysis to the faint tail
of the parameters space.
3) Perform spectro-photometric analysis on individual and stacked Euclid data and derive
physical properties for different galaxy populations (i.e. “normal” star-forming galaxies,
passive galaxies and AGN). Study the evolution of scaling relations (e.g. mass-age,
mass-metallicity) with redshift and the possible dependence on environment.
4) Compare the results to state-of-the-art theoretical models (e.g. GAEA), in order to put them
into the broader context of galaxy evolution.
5) Publish the scientific results and make the new tools available to the wider community
through their implementation into the ESA datalabs.
The PhD project will be carried out as part of the Euclid Legacy Science Advanced Analysis Tools
(ELSA) program, an HORIZON-EU funded project (PI: M. Talia) aimed at exploring new
methodologies and creating cutting-edge pipelines, tools and algorithms in order to maximally
exploit the legacy value of Euclid spectroscopic data for galaxy evolution studies. In particular, the
successful applicant will work in the framework of the Work Package 2 (1D-spectra) and in close
collaboration with ELSA team members both in Bologna (namely S. Quai and A. Enia at DiFA and L.
Pozzetti and M. Bolzonella at INAF-OAS) and in the other institutes that are part of the
collaboration. ELSA membership will give access to reserved computational resources of the cluster
inside the Open Physics Hub (OPH) at DiFA. Also, the PhD student will enter the Euclid
collaboration and gain priority access to all the data collected by the telescope.
 PhD project in ASTROPHYSICS

Title of the Project: Investigating stellar rotation in low and intermediate mass stars

Supervisor : Marco Tailo

Co-Supervisors : Andrea Miglio

Scientific Case: Stellar evolution (SE) is fundamental in astrophysics, astrobiology, and

planetology. This is further underscored by the fact that stars are the main building blocks
of galaxies and the source of the elements essential for life and planets. Understanding
stellar evolution relies on comparing observational data with theoretical models, but
these models still have significant limitations. A key example is the discrepancy between
the observed stellar rotation rates, which are at least three times lower than predicted by
the most advanced models (see the figure in this section). Solving this issue is crucial,
especially for low- and intermediate-mass stars (LIMS), which make up the majority of
stars in the universe.

Accurate modeling of LIMS

is essential for many fields:
from understanding dust
emission and galaxy
evolution, to the study of
globular clusters - where,
at the time of this writing,
explaining the formation of
their multiple stellar
populations remains a
major challenge — and the
calibration of “chemical
clocks” used in galactic
archaeology. However, the
interaction between core
rotation, element
transport, and surface
chemistry is still poorly
explored and could offer new perspectives in astrophysics and hydrodynamics.

Outline of the Project: The aim of this project is to study rotation in stars of low and
intermediate mass and how it affects the surface chemistry and the physical features of
these stars. The research activities needed for its completion will be performed within the
framework of the Asterochronometry group, led by Prof. Andrea Miglio.
The project can be roughly divided into three main parts.

● Phase One: the student will start learning stellar evolution by using the powerful
MESA code and other essential tools for modeling and analysing stellar models
 with rotation. These new skills will be used right away, with a hands-on theoretical
investigation into how surface abundances in stars are shaped by rotational
mixing—or its absence—and by the various physical prescriptions available in
MESA.
● Phase Two: The focus shifts to evolved stars, exploring how rotation influences
their evolution and properties. Special attention will be given to core helium-
burning stars, whose unique characteristics play a crucial role in the galactic
ecosystem.
● Phase Three: The final stage broadens the horizon to a comprehensive study of
stellar rotational velocities and the mechanisms that govern them. The spotlight
will be on the internal structure of stars and how it shapes asteroseismic signals—
key for interpreting data from upcoming space missions like PLATO and HAYDN.

Contacts:
marco.tailo@unibo.it
andrea.miglio@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project:

Studying the magnetic connection between the cosmic
web and the primordial Universe
La connessione magnetica tra il cosmic web e l’Universo
primordiale
Supervisor : Prof. F. Vazza (Università di Bologna)
Co-supervisor: Dr. E. Carretti (IRA/INAF)

ScientiEic Case: New radio observations of the Faraday

Rotation effect from distant galaxies shining polarised radio
emission through the cosmic web have lead to a tantalising
detection of the signature of primordial magnetic ;ields
(Carretti, Vazza et al. 2024).
A robust detection of primordial magnetic ;ields in the local
Universe is of pivotal importance, since primordial magnetic
;ields could only be generated during out-of-equilibrium
transitions in the very early Universe, like the Electro-Weak
phase transition or before the con;inement of Quarks, in the Quark-Gluon plasma stage
of the Universe (less than a micro-second after the big bang). Primordial magnetic ;ields
have also been proposed as a plausible explanation for the detected background of
stochastic gravitational waves (Neronov et al. 2021), and hence can represent a very
powerful probe of extremely early high-energy cosmological processes, extending our
observational capabilities much beyond the epoch probed by photons of the cosmic
microwave background.
In order to accurate model the Faraday Rotation of the cosmic web, advanced and
realistic cosmological are required, so that the magnetic contamination from evolving
galaxies and radio jets can be removed, and the primordial signal can be best extracted.
To best match the large volume and level of detail proved by new radio surveys, like from
LOFAR, ASKAP and in preparation to the future ones by the Square Kilometre Array
(from 2029), new and ambitious cosmological simulations should be deployed on High
Performance Computing facilities. Thanks to new simulations, the PhD candidate will
be able to test different realistic scenarios for the origin of cosmic magnetic ;ields, with
the ;inal goal of selecting those compatible with radio observations and produce a key
result towards the understanding of cosmic magnetism.
Outline of the Project: The PhD candidate will work at the design, testing and
production of new large cosmological simulations optimised to run on large HPC
facilities like LEONARDO at Cineca. By robustly constraining the amplitude and spectral
shape of allowed primordial magnetic ;ields, the candidate will be able to produce a
key scientiEic results which can connect cosmology of the primordial Universe,
with local large-scale structures. This project calls for candidates with experience (or
curiosity) in numerics, theory and large-scale structure dynamics.

Contacts: franco.vazza2@unibo.it
 PhD project in ASTROPHYSICS

Title of the Project:

Unveiling the nature of dark matter from radio observations with SKA precursors
Rivelare la natura della materia oscura da osservazioni radio con i precursori di SKA
Supervisor : Prof. F. Vazza (Università di Bologna)
Co-supervisor: Dr. G. Bernardi (IRA/INAF), Prof. M. Regis (Università di Torino)

Scientific Case: Most of the matter in our universe must be non-baryonic. Observations
accumulated over the last few decades show that some form of dark matter (DM) is the
invisible scaffolding that holds the visible universe together. The remarkable and indisputable
evidence is still accompanied by an aura of mystery about the particle origin of dark matter.
Weakly Interacting Massive Particles (WIMP) and axion-like particles are best-motivated
dark matter candidates. WIMPs can
annihilate producing electron/positron pairs
which, in turn, can generate synchrotron
emission in the presence of magnetic fields.
Axion-like particles can decay into radio
waves. The search for the DM radio
signature has led to no detection to date,
and the most recent observations started to
place significant constraints, probing
theoretically well-motivated WIMP and
axion models.
The advent of a new generation of sensitive
radio interferometers spanning a large
range of frequencies like LOFAR,
MeerKAT and ASKAP, offers the
opportunity to improve current upper limits
on the DM mass and, ambitiously, to
attempt a detection of the DM radio signal.

Outline of the Project: The PhD candidate will work on:

- LoFAR observations of galaxy clusters. Clusters are the most massive bound systems
in the Universe and their very extended halos can be targeted to probe a possible
non-gravitational emission from particle DM. The PhD candidate will use targets from
the publicly-available, all-sky, LoFAR LoTSS survey (or deeper observations on
single targets available in the archive)
- ASKAP and MeerKAT observations of dwarf spheroidal galaxies (dSph). DSph are
the galaxies with the largest mass-to-light ratio, offering a target nearly free of
astrophysical backgrounds where to perform particle DM searches. The PhD candidate
 will use candidates from the publicly-available, all-sky ASKAP RACS/EMU surveys,
complemented MeerKAT archive data;
- MeerKAT and JVLA observations of the Galactic center. The aim is to study the
radio/gamma-ray correlation at the Galactic center and explain the gamma/ray excess
observed by the Fermi-LAT telescope as a DM signal or a (so far unknown)
population of Galactic objects. The PhD candidate will use data available from both
MeerKAT and VLA archives in order to provide the most sensitive radio images of the
Galactic centre region to date.

The PhD candidate will develop the theoretical framework to predict the DM-induced radio
signature from each target, also using cosmological numerical simulations tailored to
reproduce the mass distribution of targets (dwarf galaxies and clusters of galaxies). With
numerical simulations, the PhD candidate will also investigate the possibility that electrons
and positrons injected by DM can seed additional large-scale radio emissions, detectable with
future radio surveys using the Square Kilometre Array.
Although radio images are the publicly available data products from the aforementioned
surveys, we anticipate that further reprocessing will be needed in order to achieve better
sensitivity on the angular scales of the DM signal. We also anticipate that the search of
DM-induced radio emission may include early surveys carried out with the SKA, whose
timing is aligned with the proposed PhD project.

Contacts: franco.vazza2@unibo.it , gianni.bernardi@inaf.it

 PhD project in ASTROPHYSICS

Title of the Project: Dual and binary super-massive black holes candidates in the
gravitational-wave era

Supervisor: C. Vignali (DIFA)

Co-supervisors: A. De Rosa (INAF-IAPS), P. Severgnini (INAF-Brera)

Scientific Case: Hierarchical models of galaxy formation predict that galaxy mergers
represent a key transitional stage of rapid super-massive black hole (SMBH) growth.
Merging SMBHs are among the loudest sources of gravitational waves (GWs) in the
Universe and will be detectable with the future large ESA mission LISA. Yet, the
connection between the merging process and enhanced AGN activity (hence the
triggering and the level of nuclear emission) remains highly uncertain, affected mainly
by the lack of a thorough census of dual AGN over cosmic time. Precise demography of
dual SMBHs and the occurrence of AGN activity is currently hampered by the adopted
detection techniques, sensitivity and spatial resolution issues, and the increasing
evidence that dual AGN at kpc scales are more heavily obscured than in isolated systems
(e.g., De Rosa et al. 2019). Despite the intensive observational efforts to search for dual
and offset AGN (where only one member of the pair is active) in the last decade, how
common they are and the link with their host galaxy properties and close environment
are still open questions. It is therefore mandatory to overcome the current limitations
through an optimal exploitation of the complementarity between observations and
numerical techniques.

Outline of the Project: The current PhD project will investigate some of the following
topics: (a) the occurrence of dual and offset AGN by cross-matching large-area
optical/near-IR survey galaxy pairs (including SDSS, LEGA-C, and the recently released
DESI catalog) with Chandra and XMM-Newton catalogs and inferring the level of nuclear
activity via multi-wavelength data and X-ray spectral analysis; (b) the presence of dual
AGN in some of the deepest X-ray fields currently available (CDF-S, CDF-N, COSMOS,
Abell2744), expanding the view to high redshift; (c) the content of dual AGN, likely
associated with intermediate-mass BHs, in dwarf galaxies using spatially resolved BPT
diagrams; (d) binary AGN candidates using X-ray and optical monitoring programs.
Eventually, the PhD candidate will be able to conduct an intensive study of the currently
known dual AGN in terms of BH mass ratio and host galaxy and environment properties.
The derived source demography and physical properties obtained through multi-
wavelength data will be interpreted and fitted into a coherent framework using state-of-
the-art numerical simulations. The PhD student will also be introduced to the analysis of
MUSE, ALMA, HST, VLT, and JWST data to fully characterize dual AGN and their hosts,
and will be included in some of the major GW collaborations (LISA, LGWA, ET).
She/he will gain significant skills in data analysis and interpretation and writing
proposals, will acquire scientific independence, will present the work at
national/international conferences, and will have the opportunity to visit renowned
research institutes and universities within the collaboration.

Contacts: C. Vignali – DIFA (cristian.vignali@unibo.it); A. De Rosa – INAF-IAPS

(alessandra.derosa@inaf.it); P. Severgnini – INAF-Brera (paola.severgnini@inaf.it)
 PhD project in ASTROPHYSICS

Title of the Project: Shedding light on the physics of the most massive, highly accreting
SMBHs at cosmic noon through a multi-wavelength study

Supervisor: C. Vignali (DIFA)

Co-supervisors: E. Piconcelli, L. Zappacosta (INAF-Osservatorio Astronomico di Roma)

Scientific Case: While the physics of accretion in quasars at low redshift has been
widely investigated in the last decades and has provided a generally accepted picture, at
high redshift the situation is far less clear. Probing accretion in luminous quasars at
z=2−4 is fundamental to investigating the strict interplay between the disc UV emission
and that of the X-ray emitting corona at the highest accretion rates, verifying whether
different accretion-disc solutions may be at play, and assessing, from a physical and
demographic perspective, the role of quasar-driven feedback in shaping galaxies in the
early times of the Universe.

Outline of the Project: In this project, accretion physics is tackled starting from the
sample of WISE/SDSS selected hyper-luminous (Lbol>1047 erg/s) quasars at z~2−4. All of
these quasars are characterized by large Eddington ratios, thus probing accretion at its
‘extremes’, and have multi-wavelength data allowing for a comprehensive investigation
of their properties. Among the many possible open issues related to nuclear accretion at
cosmic noon, we would like to focus on (a) the nature of X-ray weak quasars at z~3
(~30% of the population) and their occurrence at earlier cosmic epochs, thus providing
an interpretation in the context of accretion-disc physics of highly accreting SMBHs; (b)
the origin of the recently found correlation between parameters linking the mid-IR
emission and the optical-UV to X-ray emission; (c) the properties of quasar host galaxies
(e.g., star-formation rates, molecular gas content) via SED fitting and millimeter (ALMA)
observations; (d) the link between quasar accretion and nuclear extinction in the path to
properly investigate the claimed blow-out (feedback) phase. Further extension of this
work may include a systematic spectral analysis of z~2−4 quasars (selected also using
the recently available DESI data) in archival Chandra and XMM-Newton observations,
and the luminous quasars at z>6 of the HYPERION sample. The properties of the
analyzed quasars will be finally compared with those of local AGN to get a
comprehensive view of accretion across cosmic time. Proprietary XMM-Newton data
should also be available.

The PhD student will gain invaluable expertise in multi-wavelength data mining,
analysis, and interpretation, in preparing observing proposals, and in presenting the
work at national/international conferences. She/he will join the WISSH collaboration,
take advantage of the interactions with researchers of Italian and foreign institutes, and
pave the way for the forthcoming ground- and space-based facilities (e.g., Vera C. Rubin
Observatory, Roman Space Telescope, NewAthena).

Contacts: C. Vignali (cristian.vignali@unibo.it); E. Piconcelli (enrico.piconcelli@inaf.it);

L. Zappacosta (luca.zappacosta@inaf.it).
 PhD project in ASTROPHYSICS

Title of the Project: The realm of the high-redshift Universe unveiled by JWST

Supervisor: Cristian Vignali (DIFA)

Co-Supervisors: F. Vito (INAF-OAS), S. Marchesi (DIFA)

Scientific Case: In the last few years, the James Webb Space Telescope has revolutionized
our view of the high-redshift Universe through the discovery of a significant number of
galaxies and Active Galactic Nuclei (AGN) up to very high redshift, probing the first
hundreds million years of the Universe. Among its main discoveries, JWST has been able
to detect black holes down to about 106 M☉ at z>5, i.e. three orders of magnitude lower
than probed by the SDSS; interestingly, most of the current JWST-detected AGN (and
candidates) are host in under-massive galaxies (compared to local relations), which
suggest a complex path for AGN and galaxies in reaching the local `Magorrian relation’.
Claims of accretion-related activity have been formulated for the Little Red Dot (LRD)
population, i.e. faint AGN candidates detected by the deep JWST surveys, likely associated
with red compact sources experiencing episodes of star formation. What is currently
partially missing is a proper broad-band characterization of both AGN (candidates) and
LRD populations taking advantage of the deep X-ray exposures in e.g. the CEERS, JADES,
and Abell 2744 fields.

Outline of the Project: The main goals of the proposed PhD project are (a) to provide a
physical characterization of the AGN thus far discovered at high redshift (z>4) by JWST
using X-ray data (hence, not only catalogs) and the available rich ancillary multi-band
datasets; (b) place constraints on the accretion-related activity in the LRD and galaxy
population using X-ray data coupled with multi-band SED fitting; the comparison between
the X-ray emission and the one in radio/mid-IR has been proven to be effective in
providing indications of obscuration. This approach will then allow us to unveil the thus-
far still poorly investigated population of obscured AGN candidates at the highest redshift;
(c) provide an updated census of the dual and offset AGN population at high redshift
through a multi-wavelength approach. The recently JWST-derived higher fraction of dual
AGN at high redshift compared to low redshift, if confirmed, needs to be interpreted using
the most up-to-date model predictions, and the mechanisms driving the likely
enhancement at high redshift (larger molecular gas content? higher merger rates?) should
be investigated.
Overall, the proposed strategy will shed light on the emergence of nuclear accretion
activity in the first two billion years of the Universe and allow us to reach a comprehensive
picture of the black hole accretion rate density at z>4.

The PhD candidate will be trained in the selection and characterization of AGN, fully
exploiting the wealth of multi-wavelength data currently available. She/he will learn how
to handle, analyze, and interpret multi-band data, and will gain expertise in proposal
writing and presenting the work at international conferences. Besides, she/he will have
the opportunity to collaborate with international research groups, thus gaining invaluable
experience for a career in astrophysics.
Contacts: cristian.vignali@unibo.it; fabio.vito@inaf.it; stefano.marchesi@unibo.it.
 PhD project in ASTROPHYSICS

Title of the Project: AGN physics and demography in the XMM-Newton-Euclid Fornax
Deep Field

Supervisor: Cristian Vignali (DIFA)

Co-Supervisors: E. Piconcelli (INAF-Osservatorio Astronomico di Roma), M. Bolzonella
(INAF-OAS), L. Barchiesi (University of Cape Town)

Scientific Case:
The Euclid mission’s twofold observing strategy – a Wide Survey covering 14000 deg2
with near-IR grism spectroscopy and photometry across visual and near-IR wavelengths,
and a Deep Survey going two magnitudes fainter over 50 deg2 – will allow, among the
multiplicity of scientific goals, to systematically study large-scale structures, clusters of
galaxies, and Active Galactic Nuclei (AGN) across cosmic time. The awarded XMM-Newton
Multi-Year Heritage program (3.5Ms) has recently started observing at 40ks depth the 10
deg2 of the Euclid Deep Field Fornax, centered on the Chandra Deep Field South; coupled
with the current and forthcoming multi-wavelength coverage (e.g., ultra-deep Rubin-
LSST), this field will be a benchmark for astrophysics in the years to come. On the AGN
side, ~7000 AGN will be detected in X-rays, including ~100 at z>3; under conservative
assumptions, about 2000 AGN will allow moderate-to-good quality X-ray spectroscopy
for proper source characterization. It will then be possible to (i) trace obscured accretion
up to high redshift, (ii) study the co-evolution of AGN and their host galaxies and the role
of feedback, (iii) determine the presence of AGN in clusters of galaxies at different
redshifts, and (iv) search for proto-clusters and large-scale structures at high redshift
using AGN as tracers of massive halos.

Outline of the Project: The main goals of the proposed PhD project are (a) to create a
catalog of obscured AGN using spectral energy distribution (SED) fitting and hardness-
ratio analysis (in the low X-ray photon regime); for about one-third of the X-ray AGN, it
will be possible to adopt physically motivated models, providing insights on the geometry
and thickness of the absorbing medium. This search will allow us to derive a reliable
census of the black hole accretion rate density over a wide range of environments and
across cosmic time, thus overcoming the limitations of previous studies in terms of area,
depth, sample size, and cosmic variance; (b) to investigate the quasar evolutionary
sequence of SMBH/host galaxy co-evolution and the claimed transition of quasars from
an initial heavily dust-enshrouded phase to a ‘blow-out’ phase, when radiation and
outflows (hence ‘feedback’ processes) from the accreting SMBH blow away the dust and
gas to reveal a blue quasar hosted in a quiescent galaxy.

The PhD candidate will be trained in all the project steps, from AGN selection to their
physical characterization, using the available multi-wavelength data, in primis XMM-
Newton and Euclid. She/he will learn how to handle, analyze, and interpret multi-band
data, and will gain expertise in proposal writing and presenting the work at international
conferences. The student will be granted collaborations with internationally recognized
and active research groups.
Contacts: cristian.vignali@unibo.it; enrico.piconcelli@inaf.it; micol.bolzonella@inaf.it;
luigi.barchiesi@uct.ac.za