Relativistic global solutions of neutrino-dominated accretion flows

TL;DR

This paper presents detailed relativistic models of neutrino-dominated accretion flows around rotating black holes, revealing their physical properties and potential to power gamma-ray bursts.

Contribution

It provides the first comprehensive set of global solutions incorporating general relativity, neutrino physics, and nucleosynthesis for NDAFs with varying parameters.

Findings

Electron degeneracy significantly affects NDAFs.

Nucleosynthesis varies radially, with different elements dominating in different regions.

Most solutions produce sufficient annihilation luminosity to explain GRBs.

Abstract

Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes are plausible candidates for the central engines of gamma-ray bursts (GRBs). We investigate one-dimensional global solutions of NDAFs, taking account of general relativity in Kerr metric, neutrino physics and nucleosynthesis more precisely than previous works. We calculate sixteen solutions with different characterized accretion rates and black hole spins to exhibit the radial distributions of various physical properties in NDAFs. \iffalse We find that the gas pressure and the neutrino cooling always become dominated in the inner region for large accretion rate, $\gtrsim 0.1 M_\odot$ $\rm s^{-1}$. \fi We confirm that the electron degeneracy has important effects in NDAFs and we find that the electron fraction is about 0.46 in the outer region for all the sixteen solutions. From the perspective of the mass fraction, free nucleons, $\rm ^4He$, and $\rm ^{56}Fe$ dominate in the inner, middle, and outer region, respectively. The influence of neutrino trapping on the annihilation is of importance for the superhigh accretion ($\dot M=10M_{\odot} \rm s^{-1}$) and most of the sixteen solutions have an adequate annihilation luminosity for GRBs.