This course presents an introduction to the study of radiation transfer, evolution of HII regions (dynamics and thermal equilibrium), emission line diagnostics, and Monte Carlo radiation transfer techniques. The lectures outline the material covered in the course and that which is examinable.
The first part of the course on basic radiation transfer terms and the equation of radiation transfer follows the relevant chapters in the Rybicki & Lightman textbook. The lectures covering the development of HII regions and on determining physical properties of nebulae and the intersetellar medium follow the chapters covering the same material in the textbooks by Bruce Draine and Osterbrock & Ferland. I'll be presenting a few lectures on Monte Carlo radiation transfer techniques that I use extensively in my own research on circumstellar disks, stellar coronae, planetary atmospheres, galaxies, HII regions, the interstellar medium, and medical physics.
There are four tutorial sheets and an example "exam style" question. Please also see the Revision Quiz questions that are at the end of each lecture. Several in-class tutorials will be arranged to go over questions from the Revision Quizes, tutorial sheets and other questions arising throughout the course. The Revision Quizes and tutorial questions will not be formally graded or contribute to the module assessment, but students are strongly encouraged to work through the Revision Quizes, tutorial sheets, past exam papers, and the relevant chapters in the recommended text books.
Along with the lectures and tutorials, there is a continually assessed component to the course and this will comprise a problem set on Monte Carlo radiation transfer techniques. This will comprise 25% of the module assessment.
Prerequsites are AS2001 or AS2101. Computational Physics and/or Computational Astrophysics are recommended and will be very useful for the continually assessed component of the module.
Radiative Processes in Astrophysics by Rybicki & Lightman
Physics of the Interstellar and Intergalactic Medium by Bruce Draine
Astrophysics of Gaseous Nebulae and Active Galactic Nuclei by Osterbrock & Ferland
Introduction to Monte Carlo Radiation Transfer by Wood, Bjorkman, Whitney & Wolff PDF
This is a short booklet that we prepaperd on basic Monte Carlo radiation transfer techniques. A plane parallel isotropic scattering code and some three dimensional scattering codes are available here.
Lecture 1: Quantities PDF
Lecture 2: More quantities PDF
Lecture 3: Radiation transfer PDF
Lecture 4: Blackbody emission PDF
Lecture 5: Spectral lines PDF
Lecture 6: Einstein coefficients PDF
Lecture 7: Detailed Balance PDF
Lecture 8: Linew widths PDF
Lecture 9: Saha Equation PDF
Lecture 10: Free-Free Scattering PDF
Lecture 11: Random Walk PDF
Lecture 12: Monte Carlo Basics I PDF
Lecture 13: Monte Carlo Basics II PDF
Lecture 14: Fine Structure PDF
Lecture 15: HII Regions PDF
Lecture 16: Ionization Fronts PDF
Lecture 17: Thermal Equilibrium PDF
Lecture 18: Case A and Case B PDF
Lecture 19: Temperature & Density Diagnostics PDF
Lecture 20: Star & nebula diagnostics PDF
MNRAS paper on collision strengths: PDF
In the class some results are stated without detailed derivations, such as the Lorentz and Voigt profiles for line absorption cross sections, and Kramer's approximation for continuous absorption. Various approximations and assumprions are used to derive these formulae, such as treating an atom as a damped harmonic oscillator. Detailed derivations are given in the recommended textbook Radiative Processes in Astrophysics by Rybicki & Lightman. Also, Chapter 4 of the textbook Stellar Atomspheres by Dimitri Mihalas (WH Freeman & Co., 1978) is devoted to absorption (and scattering) cross sections and derivations can be found there.
You may wish to use the random number generator ran2.f from Numerical Recipes for the exmple sheet problems.
Tutorial 2: PDF Solution
Tutorial 3: PDF Solution
Tutorial 4: PDF Solution
Exam style questions: PDF