Lyman-$\alpha$ forest constraints on interacting dark sectors

TL;DR

This paper introduces a new method to analyze Lyman-alpha forest data for constraining interacting dark matter models without relying on hydrodynamical simulations, providing new bounds and compatibility insights.

Contribution

A novel estimator for the Lyman-alpha flux power spectrum that reduces reliance on complex simulations and enables conservative constraints on interacting dark matter models.

Findings

Lower bounds on cannibal dark matter mass in the MeV range.

Dark matter interacting with dark radiation is compatible with BOSS Lyman-alpha data.

The new estimator is validated against hydrodynamical simulations.

Abstract

The Lyman-$\alpha$ forest is a valuable probe of dark matter models featuring a scale-dependent suppression of the power spectrum as compared to $\Lambda$CDM. In this work, we present a new estimator of the Lyman-$\alpha$ flux power spectrum that does not rely on hydrodynamical simulations. Our framework is characterized by nuisance parameters that encapsulate the complex physics of the intergalactic medium and sensitivity to highly non-linear small-scale modes. After validating the approach based on high-resolution hydrodynamical simulations for $\Lambda$CDM, we derive conservative constraints on interacting dark matter models from BOSS Lyman-$\alpha$ data on large scales, k<0.02(km/s)^(-1), with the relevant nuisance parameters left free in the model fit. The estimator yields lower bounds on the mass of cannibal dark matter, where freeze-out occurs through 3-to-2 annihilation, in the MeV range. Furthermore, we find that models of dark matter interacting with dark radiation, which have been argued to address the $H_0$ and $\sigma_8$ tensions, are compatible with BOSS Lyman-$\alpha$ data.