Andrew Wetzel edited quiescent_fraction.tex  about 9 years ago

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Figure~\ref{fig:quiescent_fraction} shows, for all satellite galaxies at $\mstar\lesssim10^9\msun$ within $300\kpc$ of the MW or M31, the fraction that are quiescent in 1-dex bins of $\mstar$ \citep[see also][]{Phillips2014, SlaterBell2014}.  We do not attempt any correction for observational completeness as a function of $\mstar$, because we measure the \emph{relative fraction} in each bin, which is likely an unbiased metric at these satellites' distances.  %absent significant differential completeness as a function of recent star formation, which is unlikely because star-forming galaxies are generally brighter, but the quiescent fraction is near unity across almost all $\mstar$.  We show fractions for allsuch  satellites (blue circles) as well as and  separately for those in the MW (violet squares) and M31 (green triangles) halos. Error bars showthe  68\% uncertainty for the binomial counts in each bin using a beta distribution \citep{Cameron2011}. Of the 56 satellites, only 4 (7\%) are star-forming/gas-rich: LMC and SMC of the MW, LGS 3 and IC 10 of M31.  Moreover, at $\mstar<8\times10^7\msun$, only 1 (LGS 3) of the 51 satellites is star-forming, and at $\mstar<9\times10^5\msun$ \emph{all} 40 satellites are quiescent.