Gas accretion onto Milky Way-like galaxies and the Local Group

SEBASTIÁN E. NUZA

Córdoba

Conferencia; Friends-of-Friends Meeting 2017 (Charla Invitada); 2017

CONICET, OAC, SECyT, ANPCyT, ICTP

Gas accretion is a fundamental process in galaxy formation as it serves to replenish galactic discs with fresh material available for star formation. One of the fundamental assumptions of chemical evolution models of the Milky Way (MW) is that larger accretion rates are expected in the past, and in the inner regions of the Galaxy, leading to the so-called ``inside-out disc formation scenario´´. Yet, this is likely the most unconstrained input in these kind of models. In this talk, I will present results concerning the gas distribution and accretion for a set of simulated MW-like halos aiming at reproducing the environmental and structural properties of the Galaxy. Our study includes simulated galaxies assuming different numerical techniques, cosmological setups and initial conditions. We find that gas accretion seems to happen in two distinct phases: an early one dominated by vertical inflows with larger accretion rates, and a subsequent phase of lower accretion rates occurring mostly radially; although this picture somewhat depends on the accretion history of the halos. Additionally, we also study how the presence of large-scale flows towards the LG barycenter may generate a dipole in the velocity map of the circumgalactic medium (CGM) as recently suggested by the velocity pattern of CGM absorption features of low, intermediate and high-ions.