A Comparison of Galacticus and COZMIC WDM Subhalo Populations

Abstract

We present a comparative analysis of warm dark matter (WDM) subhalo populations generated by the semi-analytic model {\sc Galacticus} and the COZMIC suite of dark matter-only $N$-body simulations. Using a range of thermal relic WDM particle masses (3--10 keV), we examine key summary statistics -- including the subhalo mass function, spatial distribution, maximum circular velocity $V_{\text{max}}$, and its corresponding radius $R_{\text{max}}$ -- to evaluate the consistency between these two modeling frameworks. Both models predict a suppression of low-mass subhalos correlated with decreasing WDM particle mass, and that WDM subhalos tend to have lower $V_{\text{max}}$ and larger $R_{\text{max}}$ values than their CDM counterparts at fixed mass. While {\sc Galacticus} provides more statistically precise results due to a larger sample size, the COZMIC simulations display similar qualitative trends. We discuss how differences in halo finder algorithms, simulation resolution, and modeling assumptions affect subhalo statistics. Our findings demonstrate that {\sc Galacticus} can reliably reproduce WDM subhalo distributions seen in $N$-body simulations, offering a computationally efficient tool for exploring the implications of WDM across astrophysical phenomena.

11 pages, 9 figures, Published in OJAp