The role of black hole spin and magnetic field threading the unstable neutrino disk in gamma ray bursts

¹ Copernicus Astronomical Center, Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warsaw, Poland e-mail: agnes@camk.edu.pl
² Key Laboratory for Research in Galaxies and Cosmology, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, PR China e-mail: yfyuan@ustc.edu.cn

Received: 19 June 2009
Accepted: 25 October 2009

Abstract

Aims. We report on the third phase of our study of the neutrino-cooled hyperaccreting torus around a black hole that powers the jet in gamma ray bursts. We focus on the influence of the black hole spin on the properties of the torus.

Methods. The structure of a stationary torus around the Kerr black hole is solved numerically. We take into account the detailed treatment of the microphysics in the nuclear equation of state that includes the neutrino trapping effect.

Results. We find that in the case of rapidly rotating black holes, the thermal instability discussed in our previous work is enhanced and is developed for much lower accretion rates. We also find the important role of the energy transfer from the rotating black hole to the torus via the magnetic coupling.