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Astron. Astrophys. 356, 559-569 (2000)


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Closure in flux-limited neutrino diffusion and two-moment transport

J.M. Smit 1,2, L.J. van den Horn 2,3 and S.A. Bludman 2,4,5

1 Space Research Organization Netherlands, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
2 Center for High Energy Astrophysics, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
3 Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands
4 University of Pennsylvania, Department of Physics and Astronomy, 209 South 33rd Street, Philadelphia, PA 19104-6396, USA
5 DESY, Notkestrasse 85, 22603 Hamburg DESY, Hamburg, Germany

Received 21 September 1999 / Accepted 28 January 2000

Abstract

Two-dimensional maximum entropy closure and various standard one-dimensional closures in flux-limited neutrino diffusion and two-moment transport are compared against direct numerical solutions of the neutrino Boltzmann equation. The approximate transport based on particular closures of the moment equations is rated by testing so-called weak equivalence of the first three moments of the neutrino radiation field. Additionally we consider strong equivalence of the maximum entropy angular model distribution. Our calculations are performed on two different matter backgrounds and involve several neutrino energies. As an alternative multiple energy test we look at the behavior of spectral and energy-averaged Eddington factors. Among the closures considered, two-dimensional maximum entropy closure is found to overall approximate most closely the full transport solutions.

Key words: radiative transfer – methods: numerical – stars: atmospheres – stars: neutron – stars: supernovae: general

Send offprint requests to: J.M. Smit

Correspondence to: m.smit@sron.nl

© European Southern Observatory (ESO) 2000

Online publication: April 10, 2000

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