The Phase Space and Stellar Populations of Cluster Galaxies at z ~ 1:
  Simultaneous Constraints on the Location and Timescale of Satellite Quenching
  We investigate the velocity vs. position phase space of z ~ 1 cluster
galaxies using a set of 424 spectroscopic redshifts in 9 clusters drawn from
the GCLASS survey. Dividing the galaxy population into three categories:
quiescent, star-forming, and poststarburst, we find that these populations have
distinct distributions in phase space. Most striking are the poststarburst
galaxies, which are commonly found at small clustercentric radii with high
clustercentric velocities, and appear to trace a coherent ``ring" in phase
space. Using several zoom simulations of clusters we show that the coherent
distribution of the poststarbursts can be reasonably well-reproduced using a
simple quenching scenario. Specifically, the phase space is best reproduced if
satellite quenching occurs on a rapid timescale (0.1 < tau_{Q} < 0.5 Gyr) after
galaxies make their first passage of R ~ 0.5R_{200}, a process that takes a
total time of ~ 1 Gyr after first infall. We compare this quenching timescale
to the timescale implied by the stellar populations of the poststarburst
galaxies and find that the poststarburst spectra are well-fit by a rapid
quenching (tau_{Q} = 0.4^{+0.3}_{-0.4} Gyr) of a typical star-forming galaxy.
The similarity between the quenching timescales derived from these independent
indicators is a strong consistency check of the quenching model. Given that the
model implies satellite quenching is rapid, and occurs well within R_{200},
this would suggest that ram-pressure stripping of either the hot or cold gas
component of galaxies are the most plausible candidates for the physical
mechanism. The high cold gas consumption rates at z ~ 1 make it difficult to
determine if hot or cold gas stripping is dominant; however, measurements of
the redshift evolution of the satellite quenching timescale and location may be
capable of distinguishing between the two.
