Properties of the DESI LRG sample from SHAM-based mock catalogs with realistic galaxy colors

We leverage the unprecedented volume of the DECam Legacy Survey DR9 photometric catalogs and cosmological N-body simulations with complete halo and subhalo assembly histories to create mock galaxy catalogs with realistic rest-frame colors for multiple redshifts covered by the DESI luminous red galaxy (LRG) sample. Our subhalo abundance matching (SHAM) + color-matching technique includes galaxy assembly bias by correlating subhalo circular velocities with r-band and W1-band rest-frame magnitudes, and g-r and g-W1 rest-frame colors with a proxy for subhalo ago at fixed luminosity. The model parameters are defined to reproduce the observed clustering signal, including the one-halo term. We assess the implications of identifying targets for the DESI LRG sample using both optical (M_r versus g-r) and infrared M_W1 versus g-W1) selection functions by applying both to magnitude-limited mock parent samples. Our model complements existing HOD-based models of LRG clustering by predicting the completeness, satellite fraction, and halo occupation statistics of the DESI LRG sample as a function of redshift.