Andrew Wetzel edited quenching_time.tex  about 9 years ago

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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 mass trend is broadly consistent the star-formation-history results of \citep{Weisz2015} that the more massive dwarf galaxies in the LG quenched more recently.  Our timescales are broadly consistent with the related analysis of \citet{SlaterBell2014}, who deduced a quenching delay time \emph{since first pericenter} of $1-2\gyr$ (which implies a delay 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}. 

%(\citeauthor{Wheeler2014}'s results are consistent with the star-forming LMC/SMC of the MW.)  At higher $\mstar$, \citet{Wetzel2013} indicate that the quenching timescale rapidly \emph{decreases} by $5\times10^9\msun$, and it continues to decline with increasing $\mstar$.  Overall, the typical environmental quenching timescales are shortest for the lowest-mass satellites and are longest for satellites with $\mstar\sim10^9\msun$, near the masses of similar to  the Magellanic Clouds.