CANDELS Sheds Light on the Environmental Quenching of Low-mass Galaxies
  We investigate the environmental quenching of galaxies, especially those with
stellar masses (M*)$<10^{9.5} M_\odot$, beyond the local universe. Essentially
all local low-mass quenched galaxies (QGs) are believed to live close to
massive central galaxies, which is a demonstration of environmental quenching.
We use CANDELS data to test {\it whether or not} such a dwarf QG--massive
central galaxy connection exists beyond the local universe. To this purpose, we
only need a statistically representative, rather than a complete, sample of
low-mass galaxies, which enables our study to $z\gtrsim1.5$. For each low-mass
galaxy, we measure the projected distance ($d_{proj}$) to its nearest massive
neighbor (M*$>10^{10.5} M_\odot$) within a redshift range. At a given redshift
and M*, the environmental quenching effect is considered to be observed if the
$d_{proj}$ distribution of QGs ($d_{proj}^Q$) is significantly skewed toward
lower values than that of star-forming galaxies ($d_{proj}^{SF}$). For galaxies
with $10^{8} M_\odot < M* < 10^{10} M_\odot$, such a difference between
$d_{proj}^Q$ and $d_{proj}^{SF}$ is detected up to $z\sim1$. Also, about 10\%
of the quenched galaxies in our sample are located between two and four virial
radii ($R_{Vir}$) of the massive halos. The median projected distance from
low-mass QGs to their massive neighbors, $d_{proj}^Q / R_{Vir}$, decreases with
satellite M* at $M* \lesssim 10^{9.5} M_\odot$, but increases with satellite M*
at $M* \gtrsim 10^{9.5} M_\odot$. This trend suggests a smooth, if any,
transition of the quenching timescale around $M* \sim 10^{9.5} M_\odot$ at
$0.5<z<1.0$.
