PRIMUS: The effect of physical scale on the luminosity dependence of galaxy clustering via cross-correlations

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