Kinetic Sunyaev-Zeldovich effect in modified gravity

TL;DR

This paper explores how modified gravity theories, specifically $f(R)$ models, affect the kinetic Sunyaev-Zeldovich effect in the cosmic microwave background, highlighting potential for using kSZ as a probe of gravity modifications.

Contribution

It provides a detailed comparison of $f(R)$ gravity predictions for the kSZ power spectrum with $ ext{Lambda}$CDM, incorporating nonlinear matter power spectrum modeling.

Findings

Modified gravity can significantly alter the kSZ signal.

Changes in structure growth rate have a larger impact than expansion history.

kSZ can serve as a complementary test for gravity theories.

Abstract

We investigate the impact of modified theories of gravity on the kinetic Sunyaev-Zeldovich (kSZ) effect of the cosmic microwave background. We focus on a specific class of $f(R)$ models of gravity and compare their predictions for the kSZ power spectrum to that of the $\Lambda$CDM model. We use a publicly available modified version of Halofit to properly include the nonlinear matter power spectrum of $f(R)$ in the modeling of the kSZ signal. We find that the well-known modifications of the growth rate of structure in $f(R)$ can indeed induce sizable changes in the kSZ signal, which are more significant than the changes induced by modifications of the expansion history. We discuss prospects of using the kSZ signal as a complementary probe of modified gravity, giving an overview of assumptions and possible caveats in the modeling.