The Annihilation Luminosity Of Neutrino-Dominated Accretion Flows

The gamma-ray burst(GRB) is the most drastic burst in the universe known so far which gamma rays from the universe increase quickly and decrease soon.In the past decade,lots of remarkable progresses have been made in observations and theoretical researches of GRBs.The fireball-shock model has been widely accepted to interpret the prompt emission and afterglow radiation of GRBs,though the central engine of the relativistic fireball is not yet well understood,but most popular models for the energy source of GRBs are in common invoking a hyperaccreting black hole.In this thesis,the observations and theoretical works of GRBs are reviewed,and my own study of a hyperaccretion model,namely the neutrino-dominated accretion flow(NDAF) model,is introduced.The first chapter reviews the observations and theoretical researches of GRBs, and several models to explain the central engine of GRBs.In the second chapter I introduce the concept and sorts of black holes and accretion disk.It briefly reviews the current progresses and situation of the black hole accretion disks' theory.Then it reviews the two hyperaccretion models of GRBs:One is that electromagnetic actions extract energies of the black hole accretion disk system; the other is the neutrino-dominated accretion flows(NDAFs) model.And I mainly introduce the progress made in NDAFs.In the third chapter,after considering the general relativistic effect,the electron fraction,the free nucleon fraction,and the electron degeneracy,we count the neutrino emission of neutrino optical thick regions,discuss how luminosity of a neutrino-cooled accretion disk in a gamma-ray burst,is determined by the disk's fundamental parameters,namely the mass of the central black hole M,the mass accretion rate M,and the viscosity parameterαin detail.We find that radiation luminosity depends mainly on M in evidence,annihilation luminosity L_?and annihilation efficiencyη_? increases with increasing M,but decreases significantly with increasing M.