Lyman-alpha power spectrum as a probe of modified gravity

TL;DR

This paper explores how the Lyman-alpha power spectrum can be used to detect signatures of modified gravity models, showing it is more sensitive to certain models like K-mouflage than others such as $f(R)$-gravity.

Contribution

It introduces an analytical model based on a truncated Zeldovich approximation to estimate the Lyman-alpha power spectrum in modified gravity scenarios, including new results for K-mouflage.

Findings

The shape of the distortion depends on the gravity model and its scale dependence.

The Lyman-alpha power spectrum is not very constraining for $f(R)$-gravity.

It could provide useful constraints for K-mouflage models.

Abstract

We investigate the impact of modified-gravity models on the Lyman-$\alpha$ power spectrum. Building a simple analytical modeling, based on a truncated Zeldovich approximation, we estimate the intergalactic medium power spectrum and the Lyman-$\alpha$ flux decrement power spectrum along the line of sight. We recover the results of numerical simulations for $f(R)$-gravity models and present new results for K-mouflage scenarios. We find that the shape of the distortion due to the modified gravity depends on the model, through the scale-dependence or not of their growth rate. This is more clearly seen in the three-dimensional power spectrum than in the one-dimensional power spectrum, where the line-of-sight integration smoothes the deviation. Whilst the Lyman-$\alpha$ power spectrum does not provide competitive bounds for $f(R)$ theories, it could provide useful constraints for the K-mouflage models. Thus, the efficiency of the Lyman-$\alpha$ power spectrum as a probe of modified-gravity scenarios depends on the type of screening mechanism and the related scale dependence it induces. The prospect of a full recovery of the three-dimensional Lyman-$\alpha$ power spectrum from data would also lead to stronger constraints and a better understanding of screening mechanisms.