Old Exam Exercise: Angular Moments and Wave Equations of Radiative Transfer

Описание: In this exam exercise we derive a 2nd order radiative transfer (moment) equation for the mean intensity assuming the Eddington approximation. We then do some additional fun work and first discuss how this is modified for a thermal+scattering source function, and then finally derive a wave equation for the radiation energy density in vacuum, and discuss what Eddington factor must be true in such vacuum for the wave speed to be the speed of light, contrasting this to equilibrium radiation situation where speed of sound is c/sqrt(3) instead.

0:00 Introduction
1:15 Deriving Moment Equation for Mean Intensity using Eddington approximation
11:30 Modification for thermal plus scattering source function
16:25 Wave equation for radiation energy density in the vacuum limit

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Parts are part of course: Radiation Processes in Astronomy
Lecturer: Prof. Dr. Jon Sundqvist
Programmes where I teach it: KU Leuven Bachelor Physics & Master Astronomy & Astrophysics, Hasselt University Bachelor Physics (as video course)

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Link to "Radiative Transfer and Radiative Processes in Astrophysics: Extended Version" playlist:
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