Effects of Local Environment and Stellar Mass on Galaxy Quenching out to
  z~3
  We study the effects of local environment and stellar mass on galaxy
properties using a mass complete sample of quiescent and star-forming systems
in the COSMOS field at $z\lesssim$ 3. We show that at $z\lesssim$ 1, the median
star-formation rate (SFR) and specific SFR (sSFR) of all galaxies depend on
environment, but they become independent of environment at $z\gtrsim$ 1.
However, we find that only for \textit{star-forming} galaxies, the median SFR
and sSFR are similar in different environments, regardless of redshift and
stellar mass. We find that the quiescent fraction depends on environment at
$z\lesssim$ 1, and on stellar mass out to $z\sim$ 3. We show that at
$z\lesssim$ 1, galaxies become quiescent faster in denser environments and that
the overall environmental quenching efficiency increases with cosmic time.
Environmental and mass quenching processes depend on each other. At $z\lesssim$
1, denser environments more efficiently quench galaxies with higher masses
(log($M/M_{\odot}$)$\gtrsim$ 10.7), possibly due to a higher merger rate of
massive galaxies in denser environments, and that mass quenching is more
efficient in denser regions. We show that the overall mass quenching efficiency
($\epsilon_{mass}$) for more massive galaxies (log($M/M_{\odot}$)$\gtrsim$
10.2) rises with cosmic time until $z\sim$ 1 and flattens out since then.
However, for less massive galaxies, the rise in $\epsilon_{mass}$ continues to
the present time. Our results suggest that environmental quenching is only
relevant at $z\lesssim$ 1, likely a fast process, whereas mass quenching is the
dominant mechanism at $z\gtrsim$ 1, with a possible stellar feedback physics.
