Liu, T (reprint author), Xiamen Univ, Dept Astron, Xiamen 361005, Fujian, Peoples R China.
A neutrino-dominated accretion flow (NDAF) around a rotating stellar-mass black hole (BH) is one of the plausible candidates for the central engine of gamma-ray bursts (GRBs). Two mechanisms, i.e., the Blandford-Znajek (BZ) mechanism and the neutrino annihilation process, are generally considered to power GRBs. Using the analytic solutions from Xue et al. and ignoring the effects of the magnetic field configuration, we estimate the BZ and neutrino annihilation luminosities as functions of the disk masses and BH spin parameters to contrast the observational jet luminosities of GRBs. Our results show that although the neutrino annihilation processes could account for most GRBs, the BZ mechanism is more effective, especially for long-duration GRBs. Actually, if the energy of the afterglows and flares of GRBs is included, then the distinction between these two mechanisms is more significant. Furthermore, massive disk mass and high BH spin are beneficial for powering the high luminosities of GRBs. Finally, we discuss possible physical mechanisms that could enhance the disk mass or neutrino emission rate of NDAFs and the relevant difference between these two mechanisms.
National Basic Research Program of China (973 Program) [2014CB845800]
; National Natural Science Foundation of China [11222328, 11233006, 11333004, 11373002, 11473022, U1331101]
; CAS Open Research Program of Key Laboratory for the Structure and Evolution of Celestial Objects [OP201305, OP201403]