The environmental dependence of gas accretion onto galaxies: quenching
  satellites through starvation
  Galaxies that have fallen into massive haloes may no longer be able to
accrete gas from their surroundings, a process referred to as 'starvation' or
'strangulation' of satellites. We study the environmental dependence of gas
accretion onto galaxies using the cosmological, hydrodynamical EAGLE
simulation. We quantify the dependence of gas accretion on stellar mass,
redshift, and environment, using halo mass and galaxy overdensity as
environmental indicators. We find a strong suppression, by many orders of
magnitude, of the gas accretion rate in dense environments, primarily for
satellite galaxies. This suppression becomes stronger at lower redshift.
However, the scatter in accretion rates is very large for satellites. This is
(at least in part) due to the variation in halocentric radius, since gas
accretion is more suppressed at smaller radii. Central galaxies are influenced
less strongly by their environment and exhibit less scatter in their gas
accretion rates. The star formation rates of both centrals and satellites show
similar behaviour to their gas accretion rates. The relatively small
differences between gas accretion and star formation rates demonstrate that
galaxies generally exhaust their gas reservoir somewhat faster at higher
stellar mass, lower redshift, and in denser environments. We conclude that the
environmental suppression of gas accretion could directly result in the
quenching of star formation.
