Andrew P. Hearin, Douglas F. Watson
We present age distribution matching, a new theoretical formalism for predicting how galaxies of luminosity L and color C occupy dark matter halos. Our model supposes that there are just two fundamental properties of a halo that determine the color and brightness of the galaxy it hosts: the maximum circular velocity Vmax, and the redshift at which the galaxy will be starved of cold gas z_starve. The halo property z_starve is intended to encompass physical characteristics of a halo's mass assembly history (MAH) that may deprive the galaxy of its cold gas supply and, ultimately, quench its star formation. These include the epochs when: (a) a halo accretes onto a larger halo, z_acc, (b) a halo reaches a characteristic mass (~10^12 Msun/h), z_char, and (c) a halo transitioned from the fast- to slow-accretion regime, z_form. A halo's z_starve value is determined by whichever of these events happens first in its MAH. The new, defining feature of the model is that, at fixed luminosity, galaxy color is in monotonic correspondence with z_starve with the larger values of z_starve being assigned redder colors. We populate the Bolshoi N- body simulation with a mock galaxy catalog based on age distribution matching, and show that the resulting mock galaxy distribution accurately describes the luminosity- and color-binned two-point correlation function of galaxies in the Sloan Digital Sky Survey (SDSS), as well as a variety of low-redshift galaxy group statistics. Our study of the property z_starve has important implications for how halo MAH influences stellar mass assembly. For example, the significance of the epoch z_form suggests a new, independent channel for so-called "mass quenching" based on the rate of halo mass accretion. We make publicly available our low-redshift, SDSS Mr<-19 mock galaxy catalog, and main progenitor histories of all z=0 Bolshoi halos, at http://logrus.uchicago.edu/~aphearin
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http://arxiv.org/abs/1304.5557
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