The impact of modified gravity on the Sunyaev-Zel'dovich effect

TL;DR

This study investigates how two modified gravity theories influence the Sunyaev-Zel'dovich effect's power spectra, revealing potential for these effects to serve as probes of gravity with upcoming observational data.

Contribution

First cosmological simulations combining both screened modified gravity and comprehensive galaxy formation models to analyze SZ effects.

Findings

tSZ and kSZ power spectra are significantly enhanced in modified gravity models.

Baryonic physics suppresses SZ power spectra, affecting model differences.

SZ power spectra can serve as probes of gravity with future surveys.

Abstract

We study the effects of two popular modified gravity theories, which incorporate very different screening mechanisms, on the angular power spectra of the thermal (tSZ) and kinematic (kSZ) components of the Sunyaev-Zel'dovich effect. Using the first cosmological simulations that simultaneously incorporate both screened modified gravity and a complete galaxy formation model, we find that the tSZ and kSZ power spectra are significantly enhanced by the strengthened gravitational forces in Hu-Sawicki $f(R)$ gravity and the normal-branch Dvali-Gabadadze-Porrati model. Employing a combination of non-radiative and full-physics simulations, we find that the extra baryonic physics present in the latter acts to suppress the tSZ power on angular scales $l\gtrsim3000$ and the kSZ power on all tested scales, and this is found to have a substantial effect on the model differences. Our results indicate that the tSZ and kSZ power can be used as powerful probes of gravity on large scales, using data from current and upcoming surveys, provided sufficient work is conducted to understand the sensitivity of the constraints to baryonic processes that are currently not fully understood.