Neutrino shadow and explosion mechanism of a gamma-ray burst

Energy deposition due to neutrino pair annihilation around a neutrino-dominated accretion flow (NDAF) and a black hole is one of the most significant energy sources of a gamma-ray burst(GRB). We calculate the energy deposition rate (EDR) in a hyperaccreting disk around a Kerr black hole by solving the 3D general relativistic radiative transfer equations for neutrinos. We obtain the following results: (i) Most of the neutrinos comes from just outside the marginally bound orbit of neutrino, which means that light-bending effects should be included and 3D radiative transfer calculations are essential. (ii) The total EDR can be changed by 2 - 3 orders if the neutrino temperature changes by only a factor of 2, which means that the general relativistic calculation of neutrino emission processes in the ergosphere is very important. (iii) The local EDR can be increased by the black hole's rotation, even in the case when the rotational energy of the black hole cannot be effectively extracted.