Thesis topic: The ongoing subcluster mergers in the heart of the Hydra I (Abel 1060) cluster

Thesis Supervisors: Magda Arnaboldi (ESO), Michael Hilker (ESO) and Enrica Iodice (INAF, OAC)





Rich environments of galaxies, like groups and clusters, are the sites where we can study the galaxies' mass assembly processes that lead to their observed structure, their stellar halos, and the intra-cluster light (ICL). This thesis aims to study galaxies in the Hydra I cluster, a benchmark environment where all these physical processes are at work. The main science goal is to obtain a set of observables for massive galaxies in the cluster core and perform a quantitative comparison between predictions of the mass assembly in cosmological simulations and observations. The study of the Hydra I cluster in the southern hemisphere is based on deep multi-band images and deep spectra, both already available.


The detailed goals are to i) detect and characterize the substructures (like tidal tails or streams) in the stellar halos of the Hydra I member galaxies, through morphology and colours; ii) extract the radial surface brightness profile and estimate the total accreted stellar mass by using a multi-component fits; iii) estimate the total luminosity of the ICL in the Hydra I cluster. The deep spectroscopy data for the galaxy outskirts provide complementary information on the stellar age, metallicity and alpha-elements abundance ([Fe/H] and [alpha/Fe]) of the stellar halos. The measurements can then be compared with theoretical predictions about the stellar populations in the extended halos and their relation with the progenitors. Furthermore, the kinematics of the discrete tracers as globular clusters, planetary nebulae and faint satellite galaxies can be used to constrain the mass profile from the central bright cluster galaxy, NGC 3311, to larger cluster radii.



Fig.1: The center of the cluster Abell 1060 , with the elliptical galaxies NGC 3311 and NGC 3309 in the center and the beautiful spiral NGC 3312