is directly calculated using simulation output) of each galaxy be the low-mass dark matter particles with which we populated the refined region of our simulation. Second, we only consider those galaxies with a stellar mass greater than 5$\times$10$^{9}$ M$_\odot$. We choose this lower limit to our stellar mass because we have found that above this mass our sample is more than 75% complete (Cen 2014). We have tested that including lower mass galaxies down to 10$^8$ M$_{\odot}$ has little quantitative and no qualitative effect on our results. Implementing these two criteria leaves 61% of the originally identified galaxies at $z$=0 in the low resolution run.

We plotted projections of the star particles of each of the galaxies identified by HOP at $z$=0 in order to verify first that HOP was identifying galaxy-like objects (with a stellar density peak), and second, that HOP was not grouping multiple galaxies together. Only a few of the galaxies above our minimum mass that HOP identified had density profiles without a strong density peak, and a small number of HOP-identified galaxies in fact had two density peaks, and one had three peaks. Both of these problems add up to a misidentification of only 2%.

In 