Fluxlimited neutrino diffusion in static stellar backgrounds
Abstract
The numerical implementation of multigroup LevermorePomraning Flux Limited Neutrino Diffusion Theory (FNDT) is presented. The behavior of this transport scheme is investigated in five static stellar models. In the calculations the feedback of the neutrino flow on the stellar matter is neglected. The evolution of the neutrino energy distribution function is followed in time, starting from an initial Local Thermodynamic Equilibrium (LTE) distribution throughout the star, until a stationary non LTE solution is reached. Spectral and frequency integrated sources, luminosities and distributions are presented. The influence of electron degeneracy on the neutrino transport is highlighted. Energy deposition in regions of the stellar models relevant to the delayed explosion mechanism is rule rather than exception. Absorption of high energy neutrinos w greater than 20 MeV depletes the high energy end of the spectrum at densities ranging down to n(10 to the 9th power) g/cubic cm. In order to simulate spectra seen by an observer at infinity, it is necessary to extend the transport calculation to this density. Emergent neutrino energy distributions are typically nonthermal. Thermal fits can be made only on the high energy tail of the spectrum. The use of fitting parameters in the evaluation of bulk luminosities may overestimate these by factors of several.
 Publication:

Neutrino Driven Neutron Star Formation
 Pub Date:
 1991
 Bibcode:
 1991ndns.rept...27C
 Keywords:

 Computer Systems Programs;
 Mass Distribution;
 Neutrinos;
 Stellar Models;
 Transport Theory;
 Angular Momentum;
 Diffusion Theory;
 Energy Distribution;
 Neutron Stars;
 Numerical Analysis;
 Particle Flux Density;
 Star Formation;
 Astrophysics