Lyman-α power spectrum as a probe of modified gravity

Abstract

We investigate the impact of modified-gravity models on the Lyman-α power spectrum. Building a simple analytical modeling, based on a truncated Zeldovich approximation, we estimate the intergalactic medium power spectrum and the Lyman-α 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-α 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-α 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-α power spectrum from data would also lead to stronger constraints and a better understanding of screening mechanisms.