Hints of dark matter-neutrino interactions in Lyman-α data

In this work we investigate the possibility that dark matter and (massive) neutrinos can interact via a simple, constant cross section. Building on previous numerical efforts, we constrain this model with Cosmic Microwave Background, Baryon Acoustic Oscillations, and, in particular, Lyman-α data. We find that the latter hint to a significant departure from Λ CDM , with a preference for an interaction strength about 3 σ away from zero. We trace the origin of this preference back to the additional tilt that the interacting scenario can imprint on the Lyman-α flux power spectrum, solving a well-known tension in the determination of this quantity between early-time and Lyman-α probes. Future work including complementary Lyman-α data as well as dedicated numerical simulations will be crucial in order to test these results.