Neutrino Diffusion within Dark Matter Spikes

TL;DR

This paper investigates how neutrino diffusion in dense dark matter regions near supermassive black holes can delay neutrino signals from astrophysical transients, potentially explaining observed neutrino delays in tidal disruption events.

Contribution

It introduces a novel effect of neutrino diffusion due to DM-neutrino scatterings in dense DM spikes, affecting neutrino timing and flux from astrophysical transients.

Findings

Neutrino diffusion can cause days-long delays in neutrino arrival times.

DM-neutrino interactions can suppress neutrino flux and cause energy loss.

Current models can explain observed neutrino delays from some TDEs.

Abstract

Multi-messenger observations of astrophysical transients provide powerful probes of the underlying physics of the source as well as beyond the Standard Model effects. We explore transients that can occur in the vicinity of supermassive black holes at the center of galaxies, including tidal disruption events (TDEs), certain types of blazars, or even supernovae. In such environments, the dark matter (DM) density can be extremely high, resembling a dense spike or core. We study a novel effect of neutrino diffusion sustained via frequent scatterings off DM particles in these regions. We show that for transients occurring within DM spikes or cores, the DM-neutrino scattering can delay the arrival of neutrinos with respect to photons, but this also comes with a suppression of the neutrino flux and energy loss. We apply these effects to the specific example of TDEs, and demonstrate that currently unconstrained parameter space of DM-neutrino interactions can account for the sizable $O$(days) delay of the tentative high-energy neutrinos observed from some TDEs.