Studio e Lavoro > Tesi di laurea

Pagina a cura di Gianni Bernardi

Nell’ambito della consolidata collaborazione con l’Università degli Studi di Bologna, IRA offre l’opportunità agli studenti di laurea triennale e magistrale di svolgere la tesi di laurea presso le proprie sedi. L’elenco degli studenti di laurea magistrale attualmente presenti all’IRA è visibile a questo link.

Qui di seguito una lista di tesi di laurea disponibili. Per maggiori informazioni su uno specifico progetto si prega di contattare il relatore della tesi. Per i referenti: il link per l’inserimento di proposte di Tesi di Laurea è accessibile da questa pagina.

Titolo della tesi Observations of the Epoch of Reionization and Cosmic Dawn with the Hydrogen Epoch of Reionization Array
Relatore Prof. Lauro Moscardini (; Dr. Gianni Bernardi (
Durata 6-8 mesi – available from February 2023
Descrizione One of the key frontiers of modern observational cosmology is to understand how the first structures grew from tiny fluctuations of the density field into the first stars and galaxies that, subsequently, ionized the intergalactic medium. Observations of the 21 cm line emitted by the neutral Hydrogen from the intergalactic medium at high redshift (6 < z < 30) is one of the best probes of the Cosmic Dawn and subsequent Epoch of Reionization.

The student will analyze observations taken with the Hydrogen Epoch of Reionization Array, a custom-built radio interferometric arrays that observes the 21 cm line in the 6 < z < 30 range. The student will work on the data calibration and foreground separation with the ultimate goal of improving the current 21 cm power spectrum, providing a better constraint on the physical properties of the first stars and galaxies – e.g., the average mass of the dark matter halo where they formed, their X-ray properties, how their star formation process started and evolve with time.

Titolo della tesi Studying the Cosmic Dawn with the 21 cm global signal
Relatore Prof. Lauro Moscardini (; Dr. Gianni Bernardi (; Dr. Marta Spinelli (
Durata 6-8 mesi – available from February 2023
Descrizione Single-dipole antennas observing at low frequency have the potential to measure the 21 cm global signal, the sky-averaged brightness temperature arising from the 21 cm transition of neutral hydrogen, and thus study the Universe at Cosmic Dawn when the formation of the first stars occurs (z ~ 20).

The thesis will consist in the analysis of the available data from Large-aperture Experiment to Detect the Dark Age (LEDA), located in Owens Valley in California, and/or simulations of the Radio Experiment for the Analysis of Cosmic Hydrogen (REACH), deployed in the Karoo radio reserve in South Africa. Both experiments aim to measure the sky-averaged 21 cm signal in the 12 < z < 30 range.

The analysis will include the development of techniques to disentangle the signal from the much stronger Galactic and extra-galactic foregrounds and the characterization of the impact of the systematic effects.

Titolo della tesi Mapping the large scale structure of the Universe with 21 cm Intensity Mapping
Relatore Prof. Lauro Moscardini (; Dr. Gianni Bernardi (; Dr. Marta Spinelli (
Durata 6-8 mesi – available from February 2023
Descrizione Intensity Mapping (IM) of the redshifted 21 cm line from neutral hydrogen is a promising technique to construct three-dimensional maps of the large-scale structure of the Universe in the post-reionization era, complementary to galaxy surveys. The central idea of IM is to measure the integrated 21 cm line emission from all galaxies that fall into a single resolution element (i.e. beam) without the need to resolve them individually. IM, therefore, allows the detection of the 21 cm emission at higher redshifts compared to standard observations of individual galaxies.

As IM observations trace the underlying matter distribution of the Universe on large scales, a 21 cm detection would place tight constraints on cosmological parameters.

The student will take an active part in the MeerKLASS IM survey of the MeerKAT radio telescope.  The MeerKLASS data cover a  300~deg^2 sky patch with the goal to observe IM up to z ~ 0.4 and new data will be available soon. Thesis activities will include (but not necessarily limited to) data analysis, foreground separation, and simulations of the expected cosmological signal.

Titolo della tesi Modeling the magnetic field in the CIZA J2242.8+5301 galaxy cluster
Relatore Prof. Annalisa Bonafede, Dr. Gabriella Di Gennaro, Dr. Chiara Stuardi (
Durata 6-8 months – available from May 2023
Descrizione Galaxy clusters are permeated with magnetic fields and ultra-relativistic particles, which are revealed by the presence of diffuse Mpc-size synchrotron emission in the radio band (namely, radio halos and relics). Currently, very little is known about the topology and the strength of the magnetic field on these Mpc scales. Polarization and Faraday rotation properties of sources embedded within galaxy clusters bring fundamental information about the magnetic fields that permeate the intra-cluster medium. Comparing these observational probes with the ones obtained from simulations allows us to enlighten our knowledge of large-scale magnetic fields in galaxy clusters.

The student will use 1-4 GHz observations of the CIZA J2242.8+5301, the famous cluster hosting the Sausage radio relic, performed with the Jansky Very Large Array (JVLA). The total intensity and polarized emission of cluster radio galaxies will be modeled using the QU-fitting and the RM-synthesis approach. Subsequently, the obtained information will be compared with semi-analytical and/or cosmological simulations of galaxy clusters in order to derive the magnetic field properties for this famous galaxy cluster. The student will develop important coding skills using different programming languages (python and IDL) and will have the opportunity to work and visit collaborators based in Hamburg (Germany).

Titolo della tesi Study of AGN feedback in a protocluster at z=1.7
Relatore Dr. Isabella Prandoni, Dr. Marisa Brienza (
Durata 5-6 months – available from May 2022
Descrizione J103025+052430 (Petric+2003, AJ, 126,15; Nanni+18, AA, 614,A121) is a giant (>700 kpc), Fanaroff–Riley II (Fanaroff & Riley 1974, MNRAS, 167,31) radio galaxy located at the center of a galaxy protocluster at redshift z=1.6987, composed of ten more galaxies (Gilli+19, A&A, 632,26; D’Amato+2020 A&A, 641,6). The source represents a very peculiar case of positive AGN mechanical feedback on large scales, at high-z. Indeed, some of the protocluster galaxies are distributed right along the edge of the eastern lobe of the radio galaxy and show significantly larger specific star formation rates with respect to the other galaxies, which is attributed to the effect of the expanding jets (Gilli+2019). To date J103025+052430 is one of the very few sources (Croft+2006, ApJ, 647,1040; Lacy+1998, MNRAS, 298,966), and the first one at z>1, where AGN jets seem to be able to trigger star formation in external galaxies. In the last years we have started a characterisation of the radio galaxy to learn more about its interaction with the surrounding environment.
The candidate will reduce new uGMRT data of the system at 350 MHz and 650 MHz and analyze them in combination with other radio data (LOFAR at 150 MHz and JVLA at 1400 MHz) and X-ray data (Chandra) in order to: 1) study the radio spectral curvature and age across the source over a broad frequency range  2) confirm the magnetic field distribution within the lobes and through a polarisation analysis 3) explore the properties of the surrounding magneto-ionic medium through RM Synthesis analysis. 
Titolo della tesi Unveiling the spectral properties of radio halos in the galaxy clusters of the LOFAR survey
Relatore Prof. Annalisa Bonafede (, Dr. Rossella Cassano (, Dr. Virginia Cuciti (
Durata 6-8 months – available from February 2022
Descrizione Radio halos in galaxy clusters are generated by relativistic electrons interacting with magnetic fields in the intra-cluster-medium (ICM). In the last decade we have demonstrated a connection between radio halos and the dynamics of galaxy clusters, suggesting that these radio sources form in the turbulent ICM when clusters merge with each other in the process of large scale structure formation. However this scenario has key predictions on the spectral properties of radio halos that have not been tested so far because of the lack of low frequency sensitive radio observations.
Thanks to the combination of the LOw-Frequency ARray (LOFAR, observing at 144 MHz) and the uGMRT (observing at 330 MHz), this thesis project will overcome this issue.
The analysis of the LOFAR data of a large sample of Planck clusters is now complete.
We also have uGMRT data at higher frequency (330 MHz) of clusters with radio halos detected with LOFAR. The aim of the Thesis is: 1) to analyise uGMRT data of these radio halos; 2) to derive the unbiased spectral properties of the population of radio halos in the LOFAR sample and 3) to test the most important prediction of current models for the formation of radio halos, i.e. that about half of these radio halos should have steep synchrotron spectra.
Titolo della tesi
Substructure lensing at milliarcsecond angular resolution
Relatore Prof. Daniele Dallacasa (, Dr. Cristiana Spingola (
Durata 6-9 months – available from March 2022
Descrizione A long-standing problem in observational cosmology is the strong discrepancy between the (high) number of sub-halos predicted by simulations and the (low) number of dwarf galaxies observed around the Milky Way. This issue has become known as “missing satellite problem”. Strong gravitational lensing is a powerful way to investigate this problem even at high redshift by means of magnification anomalies, and it provides an ultimate test to the nature of the dark matter particle (cold vs warm).

In this project, the student will perform the data reduction of new sensitive VLBI observations at milliarcsecond angular resolution of a sample of radio-loud strong lensing systems that show magnification anomalies. These systems may also show faint extended gravitational arcs. The student will use the new observational constraints from the radio imaging to improve the lens mass models and test the presence (and the nature) of substructures.

Titolo della tesi
A multi wavelength study of the Shapley Concentration Core
Relatore Prof. Daniele Dallacasa (, Dr. Tiziana Venturi (
Durata 8 months – part (1) available from Summer 2022; part (2) from the end of 2022.
Descrizione This project exploits the unique sensitivity of MeerKAT and ASKAP (both SKA precursors) observations of the central region of the Shapley Concentration (SC). The SC is the most massive supercluster in the Southern Hemisphere, where formation of massive clusters is taking place at the present cosmological epoch. This unique region of the sky allows to study the signature of cluster mergers and accretion in several astrophysical areas. The proposed project includes two main lines of research:
(1) the study of the role of the environment (massive clusters, poor clusters & groups, filaments) on the population of radio galaxies in the SC core. This will be complemented with proprietary high-quality optical photometry and spectroscopy, for a full characterization of the host galaxies;
(2) the study of the diffuse emission in the most massive cluster in the SC core (A3558).
Titolo della tesi
X-raying the core of the broad-line radio galaxy 3C 445
Relatore Prof. Cristian Vignali (, Dr. Giulia Migliori (
Durata 6-8 months – available from July 2022
Descrizione X-ray observations are a powerful tool to study the physics of Active Galactic Nuclei(AGN), understand how feeding and feedback of supermassive black holes at the center of the galaxies work, and probe the relation between accretion and ejection mechanisms in jetted AGN.

In this project, the student will analyze recent Chandra observations of the broad line radio galaxy 3C 445, together with other archival X-ray observations (XMM, Nustar). By means of spectral and timing analysis, the goal will be to identify the different components shaping the AGN core emission, probe the structure and geometry of the innermost (<1 kpc) AGN regions and investigate the interplay between the accretion and ejection processes. The thesis will be based on the analysis and interpretation of X-ray data, with the possibility to expand and include available multi-band observations of the source.

Titolo della tesi
Low frequency study of head-tail radio galaxies in galaxy clusters
Relatore Prof. Daniele Dallacasa (, Dr. Andrea Botteon (
Durata 6-8 months – available from January 2023
Descrizione Tailed radio galaxies are extended sources found in galaxy clusters that can show very peculiar morphologies. The most extreme class of these sources is represented by “head-tail” radio galaxies, that are generated when the host galaxy is moving at high velocity (up to 10^3 km/s) in the cluster. Owing to the ram-pressure from the intra-cluster medium (ICM), the radio jets of these sources are strongly curved, resulting in elongated trails of relativistic electrons and magnetic fields extended up to Mpc-scale.

The aim of the thesis work is to use state-of-the-art observations performed with LOFAR and uGMRT to study the morphological and spectral properties of head-tail radio galaxies. The analysis will allow the student to determine how magnetic fields and relativistic electrons evolve from the active black hole up to large distances from the host galaxy. By comparing these results with spectral aging models, the student will constrain the role of re-acceleration processes triggered by the interaction between the non-thermal components in the jets and the surrounding ICM.

Two theses on this subject are possible:
-One focused on the large head-tailed radio galaxy in Abell 1775, that will allow the student to investigate also the properties of the revived fossil plasma and of the radio halo present in the cluster center (Botteon et al. 2021, A&A, 649, A37)
-The other focused on the population of galaxies with extended radio tails in Abell 2255 (Botteon et al. 2020, ApJ, 897, 93 & Botteon et al. 2022, Science Advances, 8, 7623B).

Titolo della tesi
Spectral study of the double radio relic in MACS J1752.0+4440
Relatore Prof. Annalisa Bonafede (, Dr. Andrea Botteon (
Durata 6-8 months – available from January 2023
Descrizione Shock fronts triggered during galaxy cluster mergers generate bright synchrotron sources called radio relics. These emissions indicate that clusters shocks can accelerate electrons to relativistic energies and locally amplify the intra-cluster magnetic field. Nonetheless, the details of the mechanisms at play in these dilute environments are still poorly understood.

The aim of this thesis is to investigate the processes leading to the formation of the spectacular double radio relic system in the cluster MACS J1752.0+4440. The student will analyze radio observations spanning a wide range of frequencies obtained with new generation interferometers (LOFAR, uGMRT, JVLA) with the goal of performing a detailed spectral study of the two relics. The results of the spectral analysis will then be compared with aging models and possibly with available numerical simulations to constrain the formation scenario of the relics and the origin of the filamentary radio structures unveiled by the new observations.

Titolo della tesi
Structural evolution in two young radio sources
Relatore Prof. Daniele Dallacasa (, Dr. Marcello Giroletti (
Durata 6-9 months – available from February 2023
Descrizione The superior angular resolution of Very Long Baseline Interferometry is the only tool that can directly probe structural changes in extragalactic sources. This has provided evidence for the youth scenario (i.e. compact sources are compact because they have just started their evolutionary path) thanks to the estimate of advance velocities of features in VLBI images. However, only few such measurements have been obtained, and any additional observing epoch will greatly improve our constraints on these estimates, providing fundamental constraints for the jet evolution and its impact (feedback) on the host galaxy. In this project, the analysis of VLBI data obtained at high frequency for two radio galaxies in different stages of evolution (a young and a restarted source) will be analysed and compared with previous epochs for a general interpretation of the kinematics.
Titolo della tesi
Resolving the afterglows of gamma-ray bursts
Relatore Prof. Daniele Dallacasa (, Dr. Marcello Giroletti (
Durata 6-9 months – available from February 2023
Descrizione Gamma-Ray Bursts (GRBs) pinpoint the explosion of a massive star (long-duration GRB) or the merger of two compact objects (short-duration GRB). Regardless of the formation channel, a central engine is formed, which launches two oppositely directed relativistic jets. A long-lived afterglow emission, extending from γ-rays down to the radio band, is produced when the expanding jets interact with the circum-burst material. Radio observations are crucial to break the degeneracy in the afterglow modelling, and hence they are essential to derive the fundamental parameters that govern the launch and the subsequent evolution of the GRB jet, the circum-burst medium and the nature of the progenitor. Moreover, the Very Long Baseline Interferometry technique (VLBI) proved to be a unique tool to investigate nearby GRBs: in fact, only VLBI allows us to directly measure the superluminal expansion and/or the centroid displacement of the outflow. Our group is one of the leading teams for VLBI observations of GRB afterglows; depending on the nature of the event (luminosity distance, progenitor type, possible association with gravitational wave detections), we propose to carry out the imaging and the study of the physical parameters achieved with dedicated VLBI observations. At present, a few events that occurred in 2022 are under study, but new cases will regularly become available.
Titolo della tesi
A Unique Radio Window on Galaxy/AGN co-Evolution
Relatore Prof. Christian Vignali (, Dr. Isabella Prandoni (
Durata 6 months – available from February 2023
Descrizione Understanding the evolution of galaxies, from the end of the ‘dark ages’ through to the complexity and variety of systems we observe in the local Universe, remains a primary goal for observational and theoretical astrophysics. A crucial piece of the evolutionary picture is the role that active galactic nuclei (AGN) play in shaping galaxies over cosmic time. Indeed, the energy released by the AGN through radiative winds and/or radio jets is widely believed to regulate the rate of star formation in their host galaxies via so-called “AGN feedback”. However, the details of how and when this occurs remains uncertain from both an observational and theoretical perspective (e.g. see reviews by Heckman & Best 2014; Harrison 2017).
It is widely accepted that recurrent jet-mode AGN activity is a fundamental component of the lifecycle of the most massive galaxies, responsible for maintaining these as ‘old, red and dead’ (e.g. Best+06; Bower+06; Sabater+19). There is however mounting evidence that at least a fraction (~30%; Delvecchio+17) of radio-quiet (RQ) AGN (i.e. Seyfert galaxies and quasars) host compact AGN-triggered radio cores, possibly associated with mini-jets on (sub-)galactic scale (see also Maini+16; Herrera-Ruiz+16; Radcliffe+18). If mini-jets are a common feature (Jarvis+19), jet-driven feedback could play a significant role in shaping galaxy evolution even at lower stellar masses. These findings open new very exciting perspectives for next-generation radio-continuum surveys.Outline of the Project: The supervisor is actively participating and has leading roles in international legacy projects involving wide-field and/or deep radio-continuum surveys of some of the most popular extra-galactic fields (GOODS-N, COSMOS, etc.), carried out with SKA pathfinders/precursors (eMERLIN, JVLA, LOFAR, MeerKAT, ASKAP, etc.). At the depths probed by these surveys the radio sky is dominated by star-forming galaxies (SFG), and RQ AGN, while powerful radio galaxies (RG) and radio-loud quasars (RL-QSO) only represent a minor contribution (e.g. Prandoni+18). These surveys hence provide a powerful dust/gas-obscuration-free tool to:
1) get a complete census of AGN (including Compton-thick objects missed by X-ray surveys), and study how the Type-1/Type-2 AGN fractions evolve with both luminosity and redshift;
2) assess the incidence of mini-jets in RQ AGN populations and shed light on their role in shaping galaxies across cosmic time;
3) explore the AGN fueling/feedback cycle through combined radio-continuum, HI and ALMA CO line observations.The MSc thesis project will make use of data from one or more of the following surveys:
– eMERGE with JVLA and eMERLIN (see e.g. Guidetti+17; Muxlow+20)
– MIGHTEE with MeerKAT (see e.g. Jarvis+17; Delvecchio+21)
– EMU with ASKAP (see e.g. Norris+2011)
– J1030 field with JVLA, LOFAR, ALMA (see e.g. Gilli+19; D’Amato+20; Mignoli+20)
– LoTSS Deep Fields with LOFAR (see e.g. Tasse+21; Sabater+21; Mandal+21)
which offer complementary views on faint AGN populations. Through a comparative study of RQ and low (radio) luminosity RL AGN we will be able to identify common trends and systematic differences, that will shed light on the origin of the radio emission in the radio quiet population. The study will be done by combining radio data with the deep, extensive multi-band coverage (UV/optical/IR/sub-mm/X-ray) available for these fields. A multi- frequency, multi-band approach is essential to link the radio properties (radio power, size, spectrum and morphology) to the AGN (e.g. accretion rate, duty cycle) and host galaxy properties (stellar and dust mass, star formation rate, redshift, environment, etc.). In some cases, high quality (HI or optical) spectroscopy is available, allowing us to directly explore the link between radio emission and gaseous outflows.

Depending on the student’s interests and skills the focus of the thesis can vary: more weight can be given to radio or to ancillary multi-band data analysis; to theoretical or observational studies.