Topics

Below is a wish list of topics to be covered in this course. Next to each topic there are references to the sections of the relevant textbooks where the materials are covered (see list of textbooks in the syllabus). 

Overview of Properties Astrophysical Nebulae and Hot Astrophysical Plasmas

• The phases of the gas in the interstellar medium, excitation mechanisms [Spitzer §§1.1–1.3; Osterbrock §§1.5–1.7]

• The line-emitting regions of active galaxies and quasars [Osterbrock §§11–12, other sources]

• Accretion flows onto compact objects, relativistic jets, stellar coronae, the hot intracluster medium [various sources]

Background: Thermodynamic Equilibrium, Statistical Mechanics, Relativity

• The thermal (Maxwell-Boltzmann) velocity distribution of particles [Spitzer §2.3]

• Establishing a thermal particle distribution through collisions [Spitzer §2.1]

• Non-thermal (power law) energy distributions

• Statistical mechanics of classical and quantum-mechanical particles: density of states, occupation probability, and energy distribution functions. The Boltzmann, Bose-Einstein, and Fermi-Dirac occupation probability functions [R&L §1.5, Padmanabhan §§5.7–5.10, Shu §6, other sources].

• Special relativity: relativistic kinematics, Lorentz transformations, aberration and beaming, relativistic energy equation [R&L §§4.1–4.2, 4.7–4.8]

Radiative Transfer

• The radiative transfer equation (with simple applications) [Spitzer §§3.1–3.2; R&L §§1.3–1.4]

• Random walks and photon diffusion. Approximations for radiative diffusion. [R&L §1.7–1.8]

Continuum Radiation Processes

• Blackbody radiation; the Planck function and its properties [Spitzer §3.1; R&L §1.5]

• Thermal bremsstrahlung (free-free emission/absorption) [R&L §5; Spitzer §3.5]

• Synchrotron radiation; transition from (relativistic) synchrotron to (non-relativistic) cyclotron; averaging over particle energy dsitributions [R&L §§6.1, 6.2, 6.6, 6.8]

• (Inverse) Compton Scattering [R&L §§7.1–7.2] and repeated scatterings [R&L §7.4]

Thermodynamic Equilibrium Revisited

• Boltzmann and Saha equations [Spitzer §2.4; R&L §9.5]

• Collisional ionization of hydrogen [various sources]

Line Emission and Absorption

• Atomic energy levels, spectroscopic notation, and selection rules [R&L §§9.1–9.3 and other sources]

• Detailed balance, Einstein coefficients, line profile functions [Spitzer §3.2; R&L §1.6]

• Expressions for the line emission and absorption coefficients [Spitzer §3.3a,b]

• Absorption cross sections, optical depths, curve of growth [Spitzer §3.4b,c]

Collisional Excitation and Collisional and Radiative De-Excitation

• Collision rate coefficients [Spitzer §4.1a]

• Equilibrium populations in 2- and 3-level ionic systems [Spitzer §4.1b; Osterbrock §§3.5, 5.2, 5.5]

Photoionization and (Radiative) Recombination

• Populating excited states by recombination [Spitzer §4.2; Osterbrock §§2.1–2.2]

• Ionization and recombination coefficients and time scales [Spitzer §5.1a]

• Strömgren spheres [Spitzer §5.1b; Osterbock §5.8]