2014MNRAS.441.2593N

We study the gas distribution in the Milky Way and Andromeda using a constrained cosmological simulation of the Local Group (LG) within the context of the CLUES (Constrained Local UniversE Simulations) project. We analyse the properties of gas in the simulated galaxies at z = 0 for three different phases: `cold', `hot' and Hi, and compare our results with observations. The amount of material in the hot halo (Mhot ~ 4-5x10¹⁰M_☉), and the cold (Mcold(r ≲ 10kpc) ~ 10⁸M_☉) and Hi (M_H i(r\lesssim 50 kpc)~3-4×10^8  M_☉) components displays reasonable agreement with observations. We also compute the accretion/ejection rates together with the Hi (radial and all-sky) covering fractions. The integrated Hi accretion rate within r = 50kpc gives ∼ 0.2-0.3M_☉/yr, i.e. close to that obtained from high-velocity clouds in the Milky Way. We find that the global accretion rate is dominated by hot material, although ionized gas with T ≲ 10⁵K can contribute significantly too. The net accretion rates of all material at the virial radii are 6-8M_☉/yr. At z = 0, we find a significant gas excess between the two galaxies, as compared to any other direction, resulting from the overlap of their gaseous haloes. In our simulation, the gas excess first occurs at z ∼ 1, as a result of the kinematical evolution of the LG.