Timescales for Hi consumption and SFR depletion of satellite galaxies in
  groups
  We investigate the connection between the HI~content, SFR and environment of
galaxies using a hydrodynamic simulation that incorporates scaling relations
for galactic wind and a heuristic halo mass-based quenching prescription. We
run two zoom-in simulations of galaxy groups with $M_{halo}>10^{13}M_\odot$ at
z=0, selected to have quiet merger histories. We track galaxies as they become
satellites, and compute the delay time $\tau_{d}$ during which the satellites
are similar to central galaxies at a given stellar mass, and a fading time
$\tau_{f}$ during which satellites go from gas-rich and star-forming to
gas-poor and quiescent. We find $0.7< \tau_{d}< 3$ Gyr at $z=0$, and depends
inversely on the satellite halo mass at infall. At z ~ 1 we find ~$0.3<
\tau_{d} < 2$ Gyr, broadly consistent with a positive correlation with the
Hubble time. For a given halo mass, lower stellar mass galaxies at infall time
have higher $\tau_{d}$. We generally find $\tau_{f}\ll \tau_{d}$, ranging
between ~ 150 Myr at z~0 and ~ 80 Myr at z ~ 1 based on linear interpolation,
with some uncertainty because they are smaller than our simulation output
frequency ($200-300$ Myr). $\tau_{f}$ has no obvious dependency on infall halo
mass. Both timescales show little difference between HI depletion and SF
quenching, indicating that using up the gas reservoir by star formation without
refilling is the main mechanism to transform satellite galaxies at these halo
masses. At a given physical distance from the center of the main halo of
interest, higher redshift galaxies have on average higher cold gas content, but
the ratio of gas (HI or H$_2$) to star formation rate is similar, indicating
that star formation is consistently fed through reservoirs of HI then H$_2$.
For a given amount of HI, galaxies have shorter consumption times in more
massive halo structures.
