Cosmological simulations with hydrodynamics of screened scalar-tensor gravity with non-universal coupling

TL;DR

This study uses hydrodynamic cosmological simulations to explore how scalar-tensor gravity with varying coupling strengths affects dark matter and gas, aiming to identify observational differences between universal and non-universal couplings.

Contribution

It introduces a simulation-based analysis of non-universal scalar-tensor gravity effects on cosmological structures, highlighting differences from universal coupling scenarios.

Findings

Universal couplings result in smaller baryon fraction deviations than non-universal.

Deviations in density and power spectra differ significantly between dark matter and gas.

Dark matter deviations are generally larger than those in gas.

Abstract

In this paper we study the effects of letting the dark matter and the gas in the Universe couple to the scalar field of the symmetron model, a modified gravity theory, with varying coupling strength. We also search for a way to distinguish between universal and non-universal couplings in observations. The research is performed utilising a series of hydrodynamic, cosmological N-Body simulations, studying the resulting power spectra and galaxy halo properties, such as the density and temperature profiles. Results show that in the cases of universal couplings, the deviations in the baryon fraction from $\Lambda$CDM are smaller than in the cases of non-universal couplings throughout the halos. The same is apparent in the power spectrum baryon bias, defined as the ratio of gas to dark matter power spectrum. Deviations of the density profiles and power spectra from the $\Lambda$CDM reference values can differ significantly between dark matter and gas because the dark matter deviations are mostly larger than the deviations in the gas.