Cosmological simulations with disformally coupled symmetron fields

TL;DR

This paper uses N-body simulations to study how disformal couplings in symmetron gravity affect matter distribution, revealing that disformal terms can counteract conformal effects and induce scalar field oscillations in dark matter haloes.

Contribution

First implementation of disformal symmetron gravity in N-body simulations to analyze its impact on cosmological structures.

Findings

Disformal terms reduce the enhancement of the matter power spectrum caused by conformal symmetron fields.

Disformal effects make the evolution of structure slightly closer to standard gravity.

Oscillations of the scalar field are observed in the centers of dark matter haloes.

Abstract

We investigate statistical properties of the distribution of matter at redshift zero in disformal gravity by using N-body simulations. The disformal model studied here consists of a conformally coupled symmetron field with an additional exponential disformal term. We conduct cosmological simulations to discover the impact of the new disformal terms in the matter power spectrum, halo mass function, and radial profile of the scalar field. We calculated the disformal geodesic equation and the equation of motion for the scalar field. We then implemented these equations into the N-body code ISIS, which is a modified gravity version of the code RAMSES. The presence of a conformal symmetron field increases both the power spectrum and mass function compared to standard gravity on small scales. Our main finding is that the newly added disformal terms tend to counteract these effects and can make the evolution slightly closer to standard gravity. We finally show that the disformal terms give rise to oscillations of the scalar field in the centre of the dark matter haloes.