  The circumgalactic medium (CGM) of galaxies consists of a multiphase gas with
components at very different temperatures, from $10^ {4}$ K to $10^ {7}$ K. One
of the greatest puzzle about this medium is the presence of a large amount of
low-temperature ($T\sim10^4$ K) gas around quiescent early-type galaxies
(ETGs). Using semi-analytical parametric models, we describe the cool CGM
around massive, low-redshift ETGs as the cosmological accretion of gas into
their dark matter halos, resulting in an inflow of clouds from the external
parts of the halos to the central galaxies. We compare our predictions with the
observations of the COS-LRG collaboration. We find that inflow models can
successfully reproduce the observed kinematics, the number of absorbers and the
column densities of the cool gas. Our MCMC fit returns masses of the cool
clouds of about $10^5\ \rm{M}_{\odot}$ and shows that they must evaporate
during their journey due to hydrodynamic interactions with the hot gas. We
conclude that the cool gas present in the halos of ETGs likely cannot reach the
central regions and feed the galaxy star formation, thus explaining why these
passive objects are no longer forming stars.

Astrophysics of Galaxies;Cosmology and Nongalactic Astrophysics