Radiative Processes in Astrophysics

An introduction to the basic physics of astronomy and astrophysics at the graduate level. Principles of energy transfer by radiation. Elements of classical and quantum theory of photon emission; bremsstrahlung, synchrotron radiation. Compton scattering, plasma effects, atomic and molecular electromagnetic transitions. With applications to current research into astrophysical phenomena.

These are a collection of lectures covering topics in an introductory graduate astrophysics course on radiative processes. The subject matter is loosely drawn from Radiatve Processes in Astrophysics by Rybicki & Lightman.

At the end of the semester, each student will develop one new lecture on a subject of their choice to add to this website.

Class Code Repository

http://github.com/AaronParsons/astro207

Useful External References

Rybicki and Lightman, Radiative Processes in Astrophysics (course reference)
Mihalas and Mihalas, Foundations of Radiation Hydrodynamics
Osterbrock and Ferland, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei
Shu, 'The Physics of Astrophysics, Volume I: Radiation
Longair, High Energy Astrophysics
Mihalas, Stellar Atmospheres
Rutten, Radiative Transfer in Stellar Atmospheres
Eddie Baron's GRK Lectures on Radiation Transport
Tony Readhead's Notes
Feynman's Lectures on Physics, Volume II

Topics by Date

(Th, Aug. 25) Radiative Quantities (RL 1.1-1.3; Mil 1.1-1.3)

class mechanics
- syllabus
- references
  - Rybicki & Lightman
  - Astrobaki: learn better by teaching
- tools for figuring stuff out
  - theoretical derivation
  - order-of-magnitude estimation
  - physical intuition (hands-on modeling, analogies)
  - numerical simulation
- programming
  - Python Installation and Basic Programming
  - Revision Control (class repository)
Topics
- Specific Intensity
Activities
- convert photon number density to specific intensity

(Tu, Aug. 30) radiative transport (RL 1.4; Mil 2.1-2.2)

Topics
Activities
Activities
- sliding pennies
- tree leaves
- locust swarm
Problem Set 1 assigned
- vega_spectrum.dat
- bessel_V.dat

(Th, Sep. 3) radiative transport (RL 1.4; Mil 2.1-2.2)

Topics:
Activities
- sliding pennies
- tree leaves
- locust swarm

(Tu, Sep. 8) thermodynamic equilibrium (RL 1.5)

Topics
- Boltzmann distribution
- Black-Body Radiation (and Kirchoff's Law)
- Local Thermodynamic Equilibrium
- Maxwellian velocity distribution
Activities
- flipping pennies, rolling dice
- types of temperature
Problem Set 2 Assigned

(Th, Sep. 10) semi-classical hydrogen

Topics:
- Classical Bohr Atom
Activities
- rederivation
- Rydberg
- dipoles/quadrupoles

(Tu, Sep. 15) Einstein coefficients

Topics:
- Einstein Coefficients
- Radiative Equilibrium
Activities
- estimating Einstein A for Ly-alpha
- effective photon absorption crosssection
Problem Set 3 Assigned

(Th, Sep. 17) radiation from accelerating charges (RL 3.3-3.4)

Topics
- Larmor Formula
- Estimating Atomic Transition Strengths
- radiative dipole transitions
- photoexcitation cross-section
Activities
- Einstein A for CO

(Tu, Nov. 10) molecular lines (RL 11)

Topics
- Rovibrational Transitions
Activities
Problem Set 7 Assigned

(Tu, Sep. 22) spectral line broadening

Topics
- Fourier Transform
- Line Profile Functions
Activities
- continue molecular cloud of CO derivation
- what can you learn from a spectral line
Problem Set 4 assigned

(Th, Nov. 12) masers

Topics
- Masers
- Zeeman splitting
Activities

(Th, Sep. 24) collisional excitations

Topics:
- Collisional Excitations
- Detailed Balance
Activities
- more CO molecular cloud
- collisional line-driven cooling

(Tu, Oct. 6) free-free emission

Topics
- Thermal Bremsstrahlung (RL 5.1-5.3)
- Opacity
- Kramer's Opacity
Activities
- free-free polarization
- simulating a free-free interaction
Problem Set 5 assigned

(W, Oct. 7) radiative equilibrium (RL 1.7-1.8; Mil 2.3-2.5)

Topics:
Activities
- timescale for photons/electrons to diffuse through a neutral IGM

(Th, Oct. 8) bound-free transitions

Topics
- Milne Relation
- Saha Equation

Activities
- stromgren spheres
- recombination coefficients
- work out in detail redshift of recombination

(Tu, Oct. 13) LTE and non-LTE

Topics
- On-the-spot Approximation
- statistical equilibrium
- photoionization equilibrium
- collisional ionization equilibrium
Activities
- estimating recombination coefficients

(Tu, Oct. 13) Maxwell's Equations and Plane Waves

Topics
- Maxwell Equations for Electromagnetic Waves
- Electromagnetic Plane Waves
- Energy Density of Electromagnetic Waves

(Th, Oct. 15) plasma effects

Topics
- Plasma Frequency
- dispersion measure
- polarization
- Faraday rotation (RL 8.1-8.2)
Activities
- start de-dispersion coding

- pulsar.dat

(Tu, Oct. 20) compton scattering

Topics
- Lorentz transformations
- Doppler shift
- radiation from relativistic charges (RL 4.1, 4.2, 4.8; Grif 10.1)
- Compton Scattering
Activities
- relativistic intuition, velocity raptor
Problem Set 6 Assigned

(Th, Oct. 22) Inverse Compton scattering

Topics:
- Inverse Compton Scattering
- SZ Effect (RL 7.1-7.5)
Activities
- single scattering versus ensemble scattering
- compton saturation

(Tu, Oct. 27) relativistic transformations

Topics:
Activities
- re-deriving synchrotron critical frequency

(Th, Oct. 29) synchrotron radiation

Topics
Activities
- re-deriving synchrotron spectrum
- phenomenological description of synchrotron decay

(Tu, Nov. 3) self-absorption

Topics
Activities

(Th, Nov. 5) dust and grains

Topics:
- Dust Absorption and Scattering
- dust formation/sublimation
Activities

(Tu, Nov. 17) radiative diffusion

Topics:
- Radiative Diffusion
- bolometric radiative equilibrium
- greenhouse effect
Activities