Andrew Wetzel edited simulations.tex  about 9 years ago

Commit id: ca75222905c2bc9ebfb32d3719ff6a5e07627c56

deletions | additions      

       

ELVIS identifies dark-matter (sub)halos using the six-dimensional halo finder \textsc{rockstar} \citep{Behroozi2013a} and constructs merger trees using the \textsc{consistent-trees} algorithm \citep{Behroozi2013b}.  For each halo, we assign a virial mass, $\mvir$, and radius, $\rvir$, according to \citet{BryanNorman1998}.  A ``subhalo'' is a halo whose center is inside $\rvir$ of a more massive host halo, and a subhalo experiences ``first infall'' and becomes a ``satellite'' when it first \emph{first}  passes within $\rvir$. For each subhalo, we compute the peak mass, $\mpeak$, that it ever reached, and we assign $\mstar$ to subhalos based on their $\mpeak$ using the relation from abundance matching in \citet{GarrisonKimmel2014}, which reproduces the observed mass function at $\mstar<10^9\msun$ in the LG if one accounts for observational incompleteness \citep{Tollerud2008, Hargis2014}.  %While the relation between $\mstar$ and subhalo $\mpeak$ for dwarf galaxies remains highly uncertain, likely with significant scatter, in this work the relation is important \emph{only} in assigning infall time distributions to satellites in a 1-dex bin of $\mstar$.  %As \citet{Wetzel2015} showed, satellite infall times generally change by $<10-20\%$ over $\sim 1$ dex in $\mstar$.