Neutrino production and transport during gravitational collapse

[摘要] The P-N method is developed to describe the transport of neutrinosin collapsing stellar cores, and the multigroup flux limited diffusionand equilibrium diffusion approximations are obtained from it. Aneffective Lagrangian for weak neutral and charged current neutrinointeractions which is applicable to low energy neutrino processes isderived. The neutrino source functions which enter into the P-N equationsare given a many body theory formulation in terms of weak current-currentcorrelation functions. Within this framework, we deal, in turn,with the scattering reactions νA → νA, νA → νA*, νN → νN (both for non-degenerateand degenerate nucleons), νe → νe, and νν → νν, and the productionand absorption reactions e^-p ⇄ nν_e, e⁺n ⇄ pν_e, e^-AZ ⇄ A(Z-1) v_e,e⁺e^- ⇄ νν, and γ_pl ⇄ νν. These equations are then applied to the variousphases of neutrino flow during iron core collapse: the transparent stageto the onset of trapping; the approach of electron neutrinos to beta-equilibrium;the evolution of the muon neutrino and antineutrino distributionfunctions towards the Fermi-Dirac form; the conditions underwhich ν_ν v_µ radiative energy loss exceeds the v_e loss; comparison of theP-1 and flux limited diffusion methods of spatial transport in a staticpre-bounce core.

[发布机构] University:California Institute of Technology;Department:Physics, Mathematics and Astronomy

[关键词] Physics