High-energy Neutrino Productions from AGN Disk Transients Impacted by Circum-disk Medium

TL;DR

This paper demonstrates that circum-disk media around AGN significantly enhance high-energy neutrino production from disk transients, potentially accounting for about 20% of the diffuse neutrino background detected by IceCube.

Contribution

It introduces the role of circum-disk media in boosting neutrino production from AGN disk transients, a factor previously overlooked in models.

Findings

Circum-disk media increase neutrino production efficiency.

Enhanced neutrino flux can contribute up to 20% to the diffuse background.

TeV-PeV neutrinos are predominantly produced in this environment.

Abstract

Various supernovae (SN), compact object coalescences, and tidal disruption events are widely believed to occur embedded in active galactic nuclei (AGN) accretion disks and generate detectable electromagnetic (EM) signals. We collectively refer to them as \emph{AGN disk transients}. The inelastic hadronuclear ($pp$) interactions between shock-accelerated cosmic rays and AGN disk materials shortly after the ejecta shock breaks out of the disk can produce high-energy neutrinos. However, the expected efficiency of neutrino production would decay rapidly by adopting a pure Gaussian density atmosphere profile applicable for stable gas-dominated disks. On the other hand, AGN outflows and disk winds are commonly found around AGN accretion disks. In this paper, we present that the circum-disk medium would further consume the shock kinetic energy to more efficiently produce high-energy neutrinos, especially for $\sim$\,TeV$-$PeV neutrinos that IceCube detects. Thanks to the existence of the circum-disk medium, we find that the neutrino production will be enhanced significantly and make a much higher contribution to the diffuse neutrino background. Optimistically, $\sim20\%$ diffuse neutrino background can be contributed from AGN disk transients.