Andrew Wetzel edited quenching_time.tex  about 9 years ago

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Both panels show shorter median quenching timescales for less massive satellites: $\sim5\gyr$ at $\mstar=10^{8-9}\msun$, $2-3\gyr$ at $\mstar=10^{7-8}\msun$, and $ < 1.5\gyr$ at $\mstar<10^7\msun$, depending on the inclusion of group preprocessing.  Moreover, the median timescale for two of the lowest $\mstar$ bins is $0\gyr$ because 100\% of those satellites are quiescent, which implies extremely rapid quenching after infall.  We next compare these statistically based quenching timescales to infall Figure~\ref{fig:quench_times} also shows infall/quenching  timescales directly measured for satellites of the MW. The 3-D orbital velocity measured for the LMC/SMC strongly suggests that they are on their first infall and passed inside $\rvir$ of the MW $\approx2\gyr$ ago \citep{Kallivayalil2013}.  Given that both remain star-forming, this places a lower limit to their quenching timescale (gray triangle), consistent with our statistical timescales.  Similarly, measurements of the 3-D orbital velocity and star-formation history for Leo I ($\mstar=5.5\times10^6\msun$) indicate that it fell into the MW halo $\approx2.3\gyr$ ago and quenched $\approx1\gyr$ ago (near its $\approx90\kpc$ pericentric passage), implying a quenching timescale of $\approx1.3\gyr$ \citep[][gray pentagon]{Sohn2013}, again consistent with our results.  Additionally, our The  mass trend in Figure~\ref{fig:quench_times}  is broadly consistent the star-formation-history star-formation-history-based  results of \citep{Weisz2015} thatthe  more massive dwarf galaxies in the LG quenched more recently. Our timescales are Also, the overall timescale is  broadly consistent with the related analysis of \citet{SlaterBell2014}, who deduced a quenchingdelay  time \emph{since since  first pericenter} \emph{pericenter}  of $1-2\gyr$ (which $1-2\gyr$, which  implies a delay quenching  time since infall of $\sim3Gyr$, though they did not examine mass dependence in detail. We also compare these timescales with previous studies of more massive satellites of other hosts.  The red squares in Figure~\ref{fig:quench_times} show the timescales from \citet{Wheeler2014}, who used nearly identical methodology, combining the the galaxy catalog from \citet{Geha2012} with satellite infall times (including group preprocessing) from the Millennium II simulation \citep{BoylanKolchin2009}.