K-mouflage at high $k$: extending the reach of $\texttt{Hi-COLA}$

TL;DR

This paper extends the exttt{Hi-COLA} simulation code to include K-mouflage screening in Horndeski gravity models, enabling detailed non-linear matter power spectrum predictions crucial for testing modified gravity theories with future galaxy surveys.

Contribution

The authors enhance exttt{Hi-COLA} to simulate K-mouflage screening in Horndeski models, allowing for non-linear regime analysis of matter clustering in modified gravity.

Findings

K-mouflage increases matter power spectrum relative to GR-$ exttt{ extLambda}$CDM.

Large-scale structure computations differ between Einstein and Jordan frames.

Dissection of factors influencing the power spectrum boost.

Abstract

The $\texttt{Hi-COLA}$ code is an efficient dark matter simulation suite that flexibly handles the Horndeski family of modified gravity models. In this work we extend the scope of $\texttt{Hi-COLA}$ to accommodate Horndeski theories with K-mouflage screening, allowing for the computation of matter power spectra in the non-linear regime in these models. We explore the boost of the dark matter power spectrum relative to GR-$\Lambda$CDM in K-mouflage gravity, and also discuss how large-scale structure computations change between the Einstein and Jordan frames. A dissection of the relative contributions of the modified background, linear growth, fifth force, and the conformal factor (a new inclusion to $\texttt{Hi-COLA}$) to the boost factor is presented. The ability of $\texttt{Hi-COLA}$ to run with general Horndeski models and multiple screening mechanisms makes it an ideal tool for testing gravity with upcoming galaxy survey data.