We investigate the velocity vs. position phase space of z \sim 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 \sim 0.5R _ { 200 } , a process that takes a total time of \sim 1 Gyr after first infall .
The poststarburst phase space is not well-reproduced using long quenching timescales ( \tau _ { Q } > 0.5 ) , or by quenching galaxies at larger radii ( R \sim R _ { 200 } ) .
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 \sim 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 .