Low Surface-Brightness Galaxy Population in the Centaurus Cluster from the VEGAS Survey

Low surface-brightness (LSB) dwarf galaxies in galaxy clusters are an interesting class of objects as their contribution to the galaxy luminosity function and their evolutionary paths are not yet clear. A subgroup of dwarf LSB galaxies called ultra-diffuse galaxies (UDGs) has been studied in several environments because their formation scenarios and dark matter content are still poorly constrained. The study of LSB galaxies allows to test the galaxy formation theories in a so far unexplored and unique parameter space. It also allows to test gravity models because LSB galaxies have the lowest stellar mass content and are strongly affected by tidal forces. In addition, a complete census of LSB galaxies is needed to test cosmological models and, in particular, to investigate the missing satellite problem. I aimed at detecting the LSB galaxies and UDGs of Centaurus cluster using wide-field deep-imaging data from the VST Early-type Galaxy Survey (VEGAS), to study how their scaling relations interface with the current formation scenarios from cosmological hydrodynamical simulations. I applied straightforward and easily installable tools to develop a semi-automatic algorithm for the detection of LSB galaxies in the g'-band image of the inner 1.4X1.6 deg^2 (1 Mpc^2) region of the Centaurus cluster centered on NGC 4696. I identified 136 LSB galaxies measuring their surface brightness radial profile at mu_g<30 mag/arcsec^2, five of them are UDGs. I fitted their surface brightness distribution and performed the isophotal analysis. Finally, I circularized the isophotes to obtain the radial surface-brightness profiles that I fitted with a 1D-Sérsic model to obtain the structural parameters of the sample LSB galaxies. I find that the sample LSB galaxies are on average redder than dwarf elliptical galaxies and have a comparable slope of the color-magnitude relation. The Kormedy relation is valid in the LSB regime too. The correlations between cluster-centric distance and surface brightnesses are in favour of an ex-situ formation of LSB galaxies, whereas the number of UDGs, which is in agreement with the UDG abundance-halo mass relation, is in favour of the in-situ formation scenario.