What can we learn from higher multipole power spectra of galaxy distribution in redshift space?

TL;DR

This paper explores the use of higher multipole power spectra of galaxy distributions in redshift space as a novel method to test gravity and galaxy velocity structures on halo scales, using a halo model and N-body simulations.

Contribution

It introduces a theoretical model for higher multipole spectra on small scales and demonstrates its effectiveness in testing gravity and galaxy dynamics on halo scales.

Findings

The model accurately fits multipole spectra from simulations.

Higher multipole spectra can be used to test gravity on small scales.

The method offers an alternative to large-scale linear growth rate tests.

Abstract

We investigate a potential of the higher multipole power spectra of the galaxy distribution in redshift space as a cosmological probe on halo scales. Based on the fact that a halo model explains well the multipole power spectra of the luminous red galaxy (LRG) sample in the Sloan Digital Sky Survey (SDSS), we focus our investigation on the random motions of the satellite LRGs that determine the higher multipole spectra at large wavenumbers. We show that our theoretical model fits the higher multipole spectra at large wave numbers from N-body numerical simulations and we apply these results for testing the gravity theory and the velocity structure of galaxies on the halo scales. In this analysis, we use the multipole spectra P_4(k) and P_6(k) on the small scales of the range of wavenumber 0.3<k/[h{Mpc}^{-1}]<0.6, which is in contrast to the usual method of testing gravity by targeting the linear growth rate on very large scales. We demonstrate that our method could be useful for testing gravity on the halo scales.