The impact of dark matter-neutrino (νDM) 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-α observations. We demonstrate that a similar observational preference is obtained if νDM interactions are primarily enhanced during a specific epoch, z∼(104−105), leading to >3σ 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.
@article{arxiv.2505.20396,
title = {Cosmological impact of $\nu$DM interactions enhanced in narrow redshift ranges},
author = {Sebastian Trojanowski and Lei Zu},
journal= {arXiv preprint arXiv:2505.20396},
year = {2025}
}