Difference between revisions of "Radiative Processes in Astrophysics"

Revision as of 13:14, 16 October 2014

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. 28) electromagnetic waves (RL 2.1-2.3; Grif 8.1)

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
- Maxwell Equations for E&M Waves
- Energy Density
- Electromagnetic Plane Waves
Activities
- Astrobaki tour
- get accounts / set up environments

(Tu, Sep. 2) radiative quantities (RL 1.1-1.3; Mil 1.1-1.3)

Topics
Activities
- estimate Bohr Atom decay
- convert photon number density to specific intensity
Problem Set 1 assigned
- vega_spectrum.dat
- bessel_V.dat

(Th, Sep. 4) radiative transport (RL 1.4; Mil 2.1-2.2)

Topics:
- Radiative Transfer Equation
- Optical Depth
- basic scattering
Activities
- sliding pennies
- tree leaves
- locust swarm

(Tu, Sep. 9) 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. 11) free-free emission

Topics
- Collisions
- Thermal Bremsstrahlung (RL 5.1-5.3)
- Kramer's Opacity
- larmor radius/frequency
- cyclotron lines
Activities
- collision rates
- normalizing the maxwellian
- Heisenberg and the FFT

(Tu, Sep. 16) semi-classical hydrogen

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

(Tu, Oct. 14) Einstein coefficients

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

(Th, Oct. 16) radiation from accelerating charges (RL 3.3-3.4)

Topics
- Estimating Atomic Transition Strengths
- radiative dipole transitions
- photoexcitation cross-section
Activities
- size of a molecular cloud optically thick in CO
Problem Set 3 Assigned

(Tu, Oct. 21) spectral line broadening

Topics
Activities
- continue molecular cloud of CO derivation
- what can you learn from a spectral line

(Th, Oct. 23) collisional excitations

Topics:
- Collisional Excitations
- Detailed Balance
Activities
- critical densities
- electron densities in the mesosphere associated with the aurora
Problem Set 4 assigned

(Th, Sep. 18) radiative equilibrium (RL 1.7-1.8; Mil 2.3-2.5)

Topics:
- Coulomb Focusing
- Central Limit Theorem
- Thomson cross-section
Activities
- timescale for photons/electrons to diffuse through a neutral IGM

(Tu, Oct. 28) bound-free transitions

Topics
- photoionization
- Saha Equation
- Milne Relation
Activities
- work out in detail redshift of recombination

(Th, Oct. 30) LTE and non-LTE

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

(Tu, Sep. 16) plasma effects

Topics
- Plasma Frequency
- dispersion measure
- polarization
- Faraday rotation (RL 8.1-8.2)
Activities
- start de-dispersion coding
Problem Set 5 assigned
- pulsar.dat

(Tu, Sep. 23) compton scattering

Topics
- Lorentz transformations
- Doppler shift
- radiation from relativistic charges (RL 4.1, 4.2, 4.8; Grif 10.1)
- Compton Scattering
Activities

(Th, Sep. 25) Inverse Compton scattering

Topics:
- Inverse Compton Scattering
- SZ Effect
Activities

(Tu, Sep. 30) relativistic transformations

Topics:
- Introduction to Synchrotron Radiation and Relativistic Beaming
- synchrotron power pattern
- synchrotron polarization
Activities

(Th, Oct. 2) synchrotron radiation

Topics
Activities

(Tu, Oct. 7) self-absorption

Topics
- synchrotron self-absorption
- synchrotron self-compton
- compton catastrophe
Activities

(Tu, Nov. 4) dust and grains

Topics:
- absorptive/scattering cross-sections
- dust formation/sublimation
- Frequency Redistribution in Non-Coherent Scattering
Activities

(Th, Nov. 6) molecular lines

Topics
- rotational transitions
- vibrational transitions
- H2 & CO
Activities

(Th, Nov. 13) masers

Topics
- Masers
Activities

(Tu, Nov. 18) radiative diffusion

Topics:
- zeeman splitting
- radiative diffusion
- bolometric radiative equilibrium
- greenhouse effect
Activities

(Th, Nov. 20) high-redshift 21cm radiation

Topics
Activities

(Tu, Dec. 2) Radiative Transfer Codes/Review 1

Review

(Th, Dec. 4) Review 2

Review

Lectures

To Do

And finally, a wish-list of edits:

Continue to break up material by subject, rather than lecture
Fix typos, errors in content
Use more words, less formulae

@@ Line 173: / Line 173: @@
 ==== (Tu, Sep. 23) compton scattering ====
 * Topics
+** [[Lorentz transformations]]
+** [[Doppler shift]]
+** radiation from relativistic charges (RL 4.1, 4.2, 4.8; Grif 10.1)
 ** [[Compton Scattering]]
-** [[SZ Effect]] (RL 7.1-7.5)
 * Activities
 **