Quenching and ram pressure stripping of simulated Milky Way satellite
  galaxies
  We present predictions for the quenching of star formation in satellite
galaxies of the Local Group from a suite of 30 cosmological zoom simulations of
Milky Way-like host galaxies. The Auriga simulations resolve satellites down to
the luminosity of the classical dwarf spheroidal galaxies of the Milky Way. We
find strong mass-dependent and distance-dependent quenching signals, where
dwarf systems beyond 600 kpc are only strongly quenched below a stellar mass of
$10^7$ M$_\odot$. Ram pressure stripping appears to be the dominant quenching
mechanism and 50% of quenched systems cease star formation within 1 Gyr of
first infall. We demonstrate that systems within a host galaxy's $R_{200}$
radius are comprised of two populations: (i) a first infall population that has
entered the host halo within the past few Gyrs and (ii) a population of
returning `backsplash' systems that have had a much more extended interaction
with the host. Backsplash galaxies that do not return to the host galaxy by
redshift zero exhibit quenching properties similar to galaxies within $R_{200}$
and are distinct from other external systems. The simulated quenching trend
with stellar mass has some tension with observations, but our simulations are
able reproduce the range of quenching times measured from resolved stellar
populations of Local Group dwarf galaxies.
