Andrew Wetzel edited observations.tex  about 9 years ago

Commit id: 00959811b6035476ef4c225a497c6cefd48f223c

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We do not include the recently discovered ultra-faint satellites of the MW from the Dark Energy Survey \citep{Koposov2015, DES2015}, though if they are all quiescent galaxies, their inclusion would not change our results.  Observed dwarf galaxies show a tight correlation between their morphology, star formation, and cold gas content: all spheroidals have little-to-no detectable cold gas or ongoing star formation, and almost all of irregulars have significant cold gas mass and ongoing star formation.  Thus, we define ``quiescent'' satellites as those that have with  $\mgas/\mstar<0.1$ or that  are classified ashaving  spheroidalmorphology  if they have no cold gas constraints. By this definition, the only star-forming, gas-rich satellitesin the LG  are: LMC ($\mstar=1.5\times10^9\msun$, $\mgas/\mstar\approx0.3$) and SMC ($\mstar=4.6\times10^8\msun$, $\mgas/\mstar\sim1$) around the MW,and  LGS 3 ($\mstar=9.6\times10^5\msun$, $\mgas/\mstar\approx0.4$) and IC 10 ($\mstar=9\times10^7$, $\mgas/\mstar\approx0.6$) around M31. %(While Sculptor has $\mgas / \mstar \approx 0.096$, we consider it quiescent based on its morphology and lack of recent star formation \citep{Weisz2014a}).  %(Dan or Erik - can you say something about comparing these cuts with either SFR metrics or SFHs? Specifically, I am glossing over any ambiguous systems? - AW  %I don't think you're glossing over anything important - Dan