PRIMUS: The Effect of Physical Scale on the Luminosity Dependence of Galaxy Clustering via Cross-correlations

We report small-scale clustering measurements from the PRIsmMUlti-object Survey (PRIMUS) spectroscopic redshift survey as a functionof color and luminosity. We measure the real-space cross-correlationsbetween 62,106 primary galaxies with PRIMUS redshifts and a tracerpopulation of ∼545,000 photometric galaxies over redshifts from z =0.2 to z = 1. We separately fit a power-law model in redshift andluminosity to each of three independent color-selected samples ofgalaxies. We report clustering amplitudes at fiducial values of z = 0.5and L=1.5{L}^*. The clustering of the red galaxies is ∼ 3times as strong as that of the blue galaxies and ∼ 1.5 as strong asthat of the green galaxies. We also find that the luminosity dependenceof the clustering is strongly dependent on physical scale, with greaterluminosity dependence being found between r=0.0625 {h}^-1{Mpc} and r=0.25 {h}^-1 {Mpc}, compared to the r=0.5{h}^-1 {Mpc} to r=2 {h}^-1 {Mpc} range. Moreover,over a range of two orders of magnitude in luminosity, a singlepower-law fit to the luminosity dependence is not sufficient to explainthe increase in clustering at both the bright and faint ends at thesmaller scales. We argue that luminosity-dependent clustering at smallscales is a necessary component of galaxy-halo occupation models forblue, star-forming galaxies as well as for red, quenched galaxies.