Hydrodynamic effects in the symmetron and f(R)-gravity models

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 Λ cold dark matter (ΛCDM) 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 ∼ 0.5 h Mpc−1. 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, but when it does, it does it to a lesser extent. 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 ΛCDM, that can be a factor of a few larger than the deviations found in density profiles and power spectra. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.