Testing Neutrino-dominated Accretion Disks From Observations For Gamma-ray Bursts

Gamma-ray bursts(GRBs) are dramatic flashes of gamma rays in the universe, which are grouped into two classes by their characteristic duration T90. Long-duration GRB(T90 > 2 s, hereafter LGRB) is widely thought to come from the gravitational collapse of a massive star and short-duration GRB(T90 < 2 s, hereafter SGRB) is related to merger events of a neutron star(NS) binary or a NS-black hole(BH) binary. All of the above scenarios may lead to the formation of a hyper-accretion disk around a stellar-mass black hole,namely the neutrino-dominated accretion flows(NDAFs) model.In this thesis, we used observational data to test the NDAFs. The first chapter is the review, the second and the third chapter are my works. The last chapter presents the urgent problems and outlook about GRBs.In the first chapter, I give an overall brief introduction to the observations of GRBs,and the development of two mainstream theoretical models of central engines of GRBs.The second chapter estimates the mean disc masses of 48 LGRBs data to investigate whether the NDAFs can power LGRBs when the reasonable BH parameters and the conversion efficiency from the neutrino annihilation to the initial fireball are adopted. The results indicate that the NDAFs are suitable to most of LGRBs if the extreme Kerr BHs exist in the central engines with the high conversion efficiency.In the third chapter, we consider the evolution of the accretion system to analyze the mean time-dependent neutrino annihilation luminosity with the different mean accretion rates and initial BH parameters. By time-integrating the luminosity, the total neutrino annihilation energy with the reasonable initial disk mass can satisfy the most of SGRBs and about half of LGRBs.The fourth chapter shows some questions still unanswered and conceiving of the further research.