Improving redshift-space power spectra of halo intrinsic alignments from perturbation theory

TL;DR

This paper develops a perturbation theory model for the redshift-space power spectra of galaxy/halo intrinsic alignments, accounting for nonlinear effects like Finger-of-God damping, to improve cosmological gravity tests.

Contribution

It introduces an analytical model for the next-to-leading order corrections of IA power spectra in redshift space, enhancing accuracy for cosmological analyses.

Findings

Model accurately predicts IA power spectra including nonlinear effects.

Corrections are crucial for unbiased growth-rate measurements.

Model validated against N-body simulations.

Abstract

Intrinsic alignments (IAs) of galaxies/halos observed via galaxy imaging survey, combined with redshift information, offer a novel probe of cosmology as a tracer of the tidal force field of a large-scale structure. In this paper, we present a perturbation theory based model for the redshift-space power spectra of galaxy/halo IAs that can keep the impact of the Finger-of-God damping effect, known as a nonlinear systematics of redshift-space distortions, under control. Focusing particularly on galaxy/halo density and an IA cross power spectrum, we derive analytically the explicit expressions for the next-to-leading order corrections. Comparing the model predictions with $N$-body simulations, we show that these corrections indeed play an important role for an unbiased determination of the growth-rate parameter, and hence the model proposed here can be used for a precision test of gravity on cosmological scales.