Detectable MeV neutrinos from black hole neutrino-dominated accretion flows

TL;DR

This paper calculates the neutrino spectra from NDAFs around black holes, showing they could be detectable by future MeV neutrino detectors if close enough, providing potential evidence for NDAFs in the universe.

Contribution

It provides detailed neutrino spectrum calculations from NDAFs considering relativistic effects and estimates detection rates for upcoming neutrino observatories.

Findings

NDAFs can produce neutrino luminosities up to 10^{50}-10^{51} erg/s.

Potential detection rate of NDAFs by Hyper-Kamiokande is up to 0.25 per century.

Detection of NDAFs would confirm their role as central engines in certain astrophysical events.

Abstract

Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes (BHs) have been theorized as the central engine of relativistic jets launched in massive star core collapse events or compact star mergers. In this work, we calculate the electron neutrino/anti-neutrino spectra of NDAFs by fully taking into account the general relativistic effects, and investigate the effects of viewing angle, BH spin, and mass accretion rate on the results. We show that even though a typical NDAF has a neutrino luminosity lower than that of a typical supernova (SN), it can reach $10^{50}-10^{51}~{\rm erg~s^{-1}}$ peaking at $\sim 10$ MeV, making them potentially detectable with the upcoming sensitive MeV neutrino detectors if they are close enough to Earth. Based on the observed GRB event rate in the local universe and requiring that at least 3 neutrinos are detected to claim a detection, we estimate a detection rate up to $\sim$ (0.10-0.25) per century for GRB-related NDAFs by the Hyper-Kamiokande (Hyper-K) detector if one neglects neutrino oscillation. If one assumes that all Type Ib/c SNe have an engine-driven NDAF, the Hyper-K detection rate would be $\sim$ (1-3) per century. By considering neutrino oscillations, the detection rate may decrease by a factor of 2-3. Detecting one such event would establish the observational evidence of NDAFs in the universe.