Neutrino Oscillation Effects on the Luminosity of Neutrino-Dominated Accretion Flows Around Black Holes

TL;DR

This paper studies how neutrino oscillations affect the luminosity and energy output of neutrino-dominated accretion flows around black holes, which are central to gamma-ray burst models.

Contribution

It introduces a detailed model incorporating neutrino oscillations into NDAF luminosity calculations, revealing their impact on neutrino annihilation energy output.

Findings

Neutrino oscillations can decrease total annihilation luminosity by up to 19%.

Electron neutrino luminosity decreases by up to 22% due to oscillations.

CP-violating phase has minimal effect on neutrino annihilation luminosity.

Abstract

The stellar-mass black hole surrounded by the neutrino-dominated accretion flow (NDAF) is proposed to be the central engine of the gamma-ray burst (GRB). In this work, we investigate the neutrino/anti-neutrino luminosity and annihilation luminosity from the NDAF and pair-annihilation model, taking into account the neutrino oscillation above the accretion disk. The disk hydrodynamical properties are modelled using the empirical solution previously derived with boundary conditions including the effect of electron degeneracy and neutrino trapping. Our key parameters are the mass accretion rate and the black hole spin given in the range of $\dot{M} = 0.1$ - $10$ $M_\odot$ s$^{-1}$ and $ 0 \le a < 1$, respectively. Without neutrino oscillation, the obtained neutrino/anti-neutrino luminosity is $\sim 10^{51}$ - $10^{53}$ $\textrm{erg s}^{-1}$, while the neutrino annihilation luminosity is found to be $\sim 10^{46}$ - $10^{51}$ $\textrm{erg s}^{-1}$. In the presence of neutrino oscillation in the vacuum limit, the electron neutrino annihilation luminosity decreases by $\lesssim 22\%$ through the flavor transformation, while the muon- and tau-neutrino luminosity can increase up to $\sim 45\%$ and $ 60\%$, respectively. As a result, the total annihilation luminosity can be reduced up to $\sim 19\%$ due to the oscillation process above the disk. Finally, we also investigate the case whereby the CP-violating phase is changed from $\delta \textrm{CP} =$ $0^{\circ}$ to $245^{\circ}$. However, our results reveal that the CP-violating phase has minimal impact on neutrino annihilation luminosity.