Cosmological impact of $\nu$DM interactions enhanced in narrow redshift ranges

TL;DR

This paper shows that dark matter-neutrino interactions, especially when enhanced during a specific redshift range, can significantly improve cosmological data fits and suggest a non-zero interaction, within a neutrino portal dark matter model.

Contribution

It introduces a redshift-specific enhancement of $ u$DM interactions that aligns with observational data and remains consistent with existing bounds, proposing a new scenario within neutrino portal models.

Findings

>3σ preference for non-zero $ u$DM interactions in combined data

Redshift-limited enhancement avoids other bounds

Resonant scattering rates achieve the enhancement

Abstract

The impact of dark matter-neutrino ($\nu$DM) interactions on cosmological perturbations has regained attention, spurred by indications of non-zero couplings from high-multipole cosmic microwave background data, weak lensing, and Lyman-$\alpha$ observations. We demonstrate that a similar observational preference is obtained if $\nu$DM interactions are primarily enhanced during a specific epoch, $z\sim (10^4-10^5)$, leading to $>3\sigma$ preference for a non-zero interaction in the combined Atacama Cosmology Telescope and cosmic shear data. This redshift-limited enhancement circumvents other cosmological and astrophysical bounds and can be achieved within a neutrino portal dark matter framework incorporating resonantly enhanced scattering rates.