Improved Fokker‐Planck Equation for Resonance‐Line Scattering
Author(s) -
G. B. Rybicki
Publication year - 2006
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.376
H-Index - 489
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/505327
Subject(s) - scattering , physics , fokker–planck equation , resonance (particle physics) , quantum electrodynamics , planck , quantum mechanics , differential equation
A new Fokker-Planck equation is developed for treating resonance linescattering, especially relevant to the treatment of Lyman alpha in the earlyuniverse. It is a "corrected" form of the equation of Rybicki & Dell'Antoniothat now obeys detailed balance, so that the approach to thermal equilibrium isproperly described. The new equation takes into account the energy changes dueto scattering off moving particles, the recoil term of Basko, and stimulatedscattering. One result is a surprising unification of the equation forresonance line scattering and the Kompaneets equation. An improved energyexchange formula due to resonance line scattering is derived. This formula iscompared to previous formulas of Madau, Meikson, & Rees (1997) and Chen &Miralda-Escud\'e (2004).Comment: 10 pages, no figures, submitted to Ap
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