# 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 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)
- Jupyter Notebooks (for visualizations and collaborating)

- Topics
- Activities
- convert photon number density to specific intensity

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

- Topics
- Activities
- Activity Sheet 2
- Activity Sheet 2 solutions
- sliding pennies

- Problem Set 1 assigned

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

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

- Activities
- Activity Sheet 3
- Activity Sheet 3 solutions
- Larmor Demo
- Impedance of free space

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

- Topics:
- 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:
- Activities
- rederivation
- Rydberg
- dipoles/quadrupoles

- Problem Set 3 Assigned

#### (Sep. 17) Einstein coefficients

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

#### (Sep. 22) spectral line broadening

- Topics
- Activities
- what can you learn from a spectral line

- Problem Set 4 Assigned

#### (Sep. 24) radiation from accelerating charges (RL 3.3-3.4)

- Topics
- Estimating Atomic Transition Strengths
- radiative dipole transitions
- photoexcitation cross-section

- Activities
- Einstein A for He+

#### (Sep. 29) molecular lines (RL 11)

- Topics
- Activities
- Einstein A for CO

- Problem Set 5 assigned

#### (Oct. 1) rovibrational transitions (RL 11)

- Topics
- Activities
- distortion in CO

#### (Oct. 6) masers

- Topics
- Activities
- masers as transistors
- laser pointers

- Problem Set 6 assigned

#### (Oct. 8) collisional excitations

- Topics:
- Activities
- more CO molecular clouds
- collisional line-driven cooling

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

#### (Oct. 20) bound-free transitions

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

#### (Oct. 22) LTE and non-LTE

- Topics
- Activities
- estimating recombination coefficients

#### (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

- Problem Set 7 assigned

#### (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

#### (Nov. 3) Inverse Compton scattering

- Topics:
- Inverse Compton Scattering
- SZ Effect (RL 7.1-7.5)

- Activities
- single scattering versus ensemble scattering
- compton saturation

- Problem Set 8 assigned

#### (Nov. 5) Synchrotron Introduction

- Topics:
- Activities
- re-deriving synchrotron critical frequency

#### (Nov. 10) Synchrotron Radiation

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

- Problem Set 9 assigned

#### (Nov. 12) Synchrotron Self-Interactions

#### (Nov. 17) dust and grains

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

- Activities
- Problem Set 10 assigned

#### (Nov. 19) radiative diffusion

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

- Activities

#### (Nov. 24) No Class

#### (Nov. 26) No Class

#### (Dec. 1) Review 1

- Review

#### (Dec. 3) Review 2

- Review

## Misc Topics

## Legacy Lecture Notes

- Radiation Lecture 01
- Radiation Lecture 02
- Radiation Lecture 03
- Radiation Lecture 04
- Radiation Lecture 05
- Radiation Lecture 06
- Radiation Lecture 07
- Radiation Lecture 08
- Radiation Lecture 09
- Radiation Lecture 10
- Radiation Lecture 11
- Radiation Lecture 12
- Radiation Lecture 13
- Radiation Lecture 14
- Radiation Lecture 15
- Radiation Lecture 16
- Radiation Lecture 17
- Radiation Lecture 18
- Radiation Lecture 19
- Radiation Lecture 20
- Radiation Lecture 21
- Radiation Lecture 22
- Radiation Lecture 23
- Radiation Lecture 24
- Radiation Lecture 25
- Radiation Lecture 26