Difference between revisions of "Radiative Processes in Astrophysics"

Revision as of 09:05, 26 August 2020

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 Radiative 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

Syllabus

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

(Aug. 27) 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
Problem Set 1 assigned
- vega_spectrum.dat
- bessel_V.dat

(Sep. 1) radiative transport (RL 1.4; Mil 2.1-2.2)

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

(Sep. 3) Maxwell's Equations and Plane Waves

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

(Sep. 8) Antennas, Bolometers, and Filters

Topics
Activities
- Fundamental Antenna Theorem
- Fourier Transforms in your head
- Impedance of free space

(Sep. 8) scattering and absorption (RL 1.4, 1.7; Mil 2.1-2.2)

Topics:
- Basic Scattering
- Central Limit Theorem
- Random Walks
- Black-Body Radiation (and Kirchoff's Law)
Activities
- photon diffusion
- high beams in fog
Problem Set 2 Assigned

(Sep. 10) thermodynamic equilibrium (RL 1.5)

Topics
Activities
- flipping pennies, rolling dice
- types of temperature

(Sep. 15) semi-classical hydrogen

Topics:
- Classical Bohr Atom
Activities
- rederivation
- Rydberg
- dipoles/quadrupoles
Problem Set 3 Assigned

(Sep. 17) Einstein coefficients

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

(Sep. 22)

Topics

(Sep. 24) spectral line broadening

Topics
- Line Profile Functions
- Zeeman splitting
Activities
- what can you learn from a spectral line
Problem Set 4 Assigned

(Sep. 29) radiation from accelerating charges (RL 3.3-3.4)

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

(Oct. 1) molecular lines (RL 11)

Topics
- Atomic and Molecular Quantum Numbers
- Rovibrational Transitions
Activities
- distortion in CO
Problem Set 5 assigned

(Oct. 6) masers

Topics
- Masers
Activities
- masers as transistors
- laser pointers

(Oct. 8) collisional excitations

Topics:
- Collisional Excitations
- Detailed Balance
Activities
- more CO molecular clouds
- collisional line-driven cooling
Problem Set 6 assigned

(Oct. 13) free-free emission

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

(Oct. 15) radiative equilibrium (RL 1.7-1.8; Mil 2.3-2.5)

Topics:
- Coulomb Focusing
- Thomson Scattering
Activities
- timescale for photons/electrons to diffuse through a neutral IGM

(Oct. 20) bound-free transitions

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

(Oct. 22) LTE and non-LTE

Topics
- Recombination Coefficients
- Review of Equilibria
Activities
- estimating recombination coefficients
Problem Set 7 assigned

(Oct. 27) plasma effects

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

(Oct. 29) 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 8 assigned
- pulsar.dat

(Nov. 3) Inverse Compton scattering

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

(Nov. 5) Synchrotron Introduction

Topics:
- Introduction to Synchrotron Radiation and Relativistic Beaming
Activities
- re-deriving synchrotron critical frequency
Problem Set 9 assigned

(Nov. 10) Synchrotron Radiation

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

(Nov. 12) Synchrotron Self-Interactions

Topics
- Synchrotron Self-Interactions
Problem Set 10 assigned

(Nov. 17) dust and grains

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

(Nov. 19) radiative diffusion

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

@@ Line 117: / Line 117: @@
 ==== (Sep. 24) spectral line broadening====
 * Topics
-** [[Fourier Transform]]
 ** [[Line Profile Functions]]
 ** [[Zeeman splitting]]