deletions | additions
diff --git a/observations.tex b/observations.tex
index a133b51..2e6b196 100644
--- a/observations.tex
+++ b/observations.tex
...
\subsection{Observations}
To
understand examine the
star-formation, cold-gas, and morphological observed properties of
the dwarf galaxies in the
Local Group, LG, we use the compilation
of observations from \citet{McConnachie2012}, which includes stellar masses, cold (atomic) gas masses, morphologies, and distances for all galaxies known at that time that are within $3 \mpc$ of the Sun.
We select ``dwarf'' galaxies as $\mstar \lesssim 10^9 \msun$, thus including the LMC ($\mstar = 1.5 \times 10^9 \msun$) but not M33 ($\mstar = 5 \times 10^{10} \msun$).
\citet{McConnachie2012} The catalog includes
distances the distance of each dwarf from both the MW and M31, and we
defined ``satellite'' galaxies define ``satellites'' as those within $300 \kpc$ of either host, motivated by the
relatively sharp transition in star formation, gas, and morphological properties within this distance.
This distance $300 \kpc$ also coincides
well with the
median virial radius, $\rvir$, for our simulated MW/M31 halos
(seeb (see below).
In addition to the data in \citet{McConnachie2012}, we also include the more recent
measurements/upper-limits measurements or upper limits of cold atomic gas mass from \citet{Spekkens2014}.
We do not include the
recently-discovered recently discovered ultra-faint satellites
of the MW from the Dark Energy Survey
(REFS). \citet{Koposov2015, DES2015}.
The observed
satellites dwarf galaxies show a tight correlation between their morphology, star formation, and cold
(atomic) gas
mass, content, such that all (?) of the dwarf spheroidals have little-to-no detectable gas ($\mgas / \mstar < 0.1$) or ongoing star formation, and all (?) of the dwarf irregulars have a significant fraction of their baryonic mass in cold
(atomic) gas and ongoing star formation.
Thus, we define ``quiescent'' satellites as those that have $\mgas / \mstar < 0.1$ or are classified as having spheroidal morphology if they have no
atomic cold gas constraints.
Thus, by this definition, the only star-forming, gas-rich satellites
in the LG are: LMC ($\mstar = 1.5 \times 10^9 \msun$, $\mgas / \mstar \approx 0.3$) and SMC ($\mstar = 4.6 \times 10^8 \msun$, $\mgas / \mstar \sim 1$) around the MW, and LGS 3 ($\mstar = 9.6 \times 10 ^ 5 \msun$, $\mgas / \mstar \approx 0.4$) and IC 10 ($\mstar = 9 \times 10 ^ 7$, $\mgas / \mstar \approx 0.6$) around M31.
While (While Sculptor has $\mgas / \mstar \approx 0.096$, we consider it quiescent based
both on its morphology and lack of
significant recent star formation
\citep{Weisz2014}. \citep{Weisz2014}).
(Dan
or Erik - can you say something about comparing these cuts with either SFR metrics or
your SFHs?) SFHs? Specifically, I am glossing over any ambiguous systems?)
In examining the fraction of
satellite dwarfs satellites that are quiescent, we
group them into
1-dex-wide 1-dex bins of $\mstar$.
We do not attempt any correction for
observational completeness
of this samples as a function of
mass, $\mstar$, but we do take into account the maximum observed
distances distance at each $\mstar$ when we compare with the simulations (see below).
