Constraining Halo Occupation Distribution and Cosmic Growth Rate using Multipole Power Spectrum

Abstract

We propose a new method of measuring halo occupation distribution (HOD) together with cosmic growth rate using multipole components of galaxy power spectrum P_l(k). The nonlinear redshift-space distortion due to the random motion of satellite galaxies, i.e., Fingers-of-God, generates high-l multipole anisotropy in galaxy clustering such as the hexadecapole (l=4) and tetra-hexadecapole (l=6), which are sensitive to the fraction and the velocity dispersion of satellite galaxies. Using simulated samples following the HOD of Luminous Red Galaxies (LRGs), we find that the input HOD parameters are successfully reproduced from P_l(k) and that high-l multipole information help to break the degeneracy among HOD parameters. We also show that the measurements of the cosmic growth rate as well as the satellite fraction and velocity dispersions are significantly improved by adding the small-scale information of high-l multipoles.