Presentation #207.06D in the session Evolution of Galaxies III.
Early-type galaxies have low specific star formation rates, old stellar populations, and little cold gas. Luminous Red Galaxies, or LRGs, were originally selected in the Sloan Digital Sky Survey as good tracers of large scale structure. Subsequent investigations have shown them to be among the most massive galaxies in the Universe, dominated by uniformly old stellar populations, and good tracers of this early-type galaxy population. Despite having old stellar populations, studies have shown that they have grown their stellar mass since z=1, implying that they grow predominantly via the accretion of satellites. This picture has not yet been tested because of the lack of deep imaging data sets that both covers a large enough area of the sky to contain substantial numbers of LRGs and also is deep enough to detect faint satellites. We present our initial characterization of the satellite galaxy population of LRGs out to z=0.65. To accomplish this we use the DESI Legacy Imaging Surveys, which are comprised of grz imaging to 2-2.5 mag deeper than SDSS and with better image quality. Specifically, we present our first measurement of the number of satellite galaxies around LRGs in bins of redshift and luminosity completeness, as well as LRG satellite color distribution. In addition, we forward model the distribution of the number of satellite galaxies that surround LRGs and constrain the average number of satellite galaxies in each bin of luminosity and redshift.