Hydrodynamic Effects in the Symmetron and $f(R)$-gravity Models

TL;DR

This study implements symmetron and $f(R)$-gravity models into a hydrodynamic N-body simulation to analyze their effects on gas and dark matter, revealing significant differences in temperature profiles compared to $\\Lambda$CDM.

Contribution

First implementation of these modified gravity models into hydrodynamic simulations, extending previous dark matter-only work to include baryonic effects.

Findings

Gas density deviations are lower than dark matter deviations in these models.

Hydrodynamic and dark matter only simulations agree on large scales ($k > 0.5$ h/Mpc).

Temperature profiles show the largest deviations from $\\Lambda$CDM, up to a factor of a few.

Abstract

In this paper we present the first results from implementing two scalar-tensor modified gravity theories, the symmetron and the Hu-Sawicki $f(R)$-gravity model, into a hydrodynamic N-body code with dark matter particles and a baryonic ideal gas. The study is a continuation of previous work where the symmetron and $f(R)$ have been successfully implemented in the RAMSES code, but for dark matter only. By running simulations, we show that the deviation from $\Lambda$CDM in these models for the gas density profiles are significantly lower than the dark matter equivalents. When it comes to the matter power-spectrum we find that hydrodynamic simulations agree very well with dark matter only simulations as long as we consider scales larger than $k\sim 0.5$ h/Mpc. In general the effects of modified gravity on the baryonic gas is found to not always mirror the effects it has on the dark matter. The largest signature is found when considering temperature profiles. We find that the gas temperatures in the modified gravity model studied here show deviations, when compared to $\Lambda$CDM, that can be a factor of a few larger than the deviations found in density profiles and power spectra.