Job & study > Master and Bachelor thesis

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.

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.

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.

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).

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.

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.

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).

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.

Depending on the student 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.