A Comparison of Galacticus and COZMIC WDM Subhalo Populations

We present a comparative analysis of warm dark matter (WDM) subhalo populations generated by the semi-analytic model 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 max , and its corresponding radius R 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 max and larger R max values than their CDM counterparts at fixed mass. While 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 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.