Physics 612

"High Energy Astrophysics"

Spring 2011

Professor: Jack Hughes, Serin 307W, 732-445-5500 x 0980 jph "at"

Meets: Tues/Fri 12:00PM-1:20PM (ARC 110)

Recommended Text: "High Energy Astrophysics" (2nd edition) by Malcolm Longair (Cambridge University Press) Vols 1 and 2. The 3rd edition is now out! Available used at

Additional Texts: "Exploring the X-ray Universe" by Charles and Seward (Cambridge); "Radiative Processes in Astrophysics" by Rybicki and Lightman (Wiley)

General Description

The Universe is filled with diverse objects and phenomena ranging from those with very low characteristic temperatures, such as the 2.7 K Cosmic Microwave Background Radiation, to the ultrahigh energy cosmic rays in which a single particle can carry 10 J or more of energy. Accordingly in order to attempt a complete understanding of cosmic objects and events, astrophysicists have been driven to conduct studies over the entire electromagnetic spectrum. In this course, the focus will be on the study of high energy astrophysics, that is to say, the field of astronomy that concerns itself with objects and phenomena having a characteristic temperature greater than about 10^6 K or equivalently 0.1 keV. This includes the X-ray and gamma-ray bands of the electromagnetic spectrum, cosmic rays, and neutrinos from the Sun and supernovae. The field is relatively new: cosmic rays were discovered in 1912 (although not explained as high energy particles until 1929) and, although, X-rays were discovered by Rongten in 1895, X-ray astronomy wasn't born until 1949 when the Sun was discovered as the first extraterrestrial X-ray source. In general the history of X-ray and gamma-ray astronomy has paralleled the history of space exploration. Neutrino astronomy is even younger, commencing with the Homestake gold mine experiment in the 1970's which gave rise to the famous "solar neutrino" problem.

This course is intended to provide the student with sufficient background material and knowledge in order to appreciate current research literature in high energy astrophysics. It will draw on graduate level physics and astronomy as prerequisites. Course material will be taken from the texts listed above. "Radiative Precesses in Astrophysics" by Rybicki and Lightman (Wiley), will be particularly helpful for the lectures on radiative processes. Students might consider looking at the readable book on X-ray astronomy "Exploring the X-ray Universe" by Charles and Seward (Cambridge).


The grading criteria for this course are divided equally between problem sets, a written observing proposal, and a presentation near the end of the course on a topic in high energy astrophysics. Each submitted proposal must conform precisely to the requirements of the most recent Announcement of Opportunity for the mission or observatory that the class, as a whole, has selected. [N.B., the class decided on Chandra proposals for either new observations or an archival study.] Criteria for grading of proposals will be based on Here in ps or pdf is an example of a successful Chandra proposal. You should choose the topic of your observing proposal in consultation with Professor Hughes. Proposals will be due on Friday April 8 at 5PM EST. As with all real proposals, this deadline will be strictly enforced.

Homework Assignments

For more information on these missions please go to their respective web sites. There is extensive material on-line for proposers.

Near-term list of topics to be covered and already completed with reading assignments

Useful references

N.B. Some of the links given below are through the Rutgers IRIS gateway and therefore may only work from RU computers

Recent results in High Energy Astrophysics

Possible topics to be covered

Overview/Historical introduction
Ionization losses of high energy particles interacting with matter
Photon interactions with matter: Photoelectric effect, Compton scattering
Photon interactions: pair production
High energy particle and photon detectors
Telescopes and Observatories
Radiative recombination (Milne relation)
Line radiation, ion & recomb rates, ionization balance
Cyclotron radiation
Synchroton radiation
Blackbody radiation
Inverse Compton scattering/Kompaneets eqn.
SNe (Supernovae): Rates/Types/progenitors/Explosion mechanisms
SNRs (Supernova Remnants): thermal emission, shock waves, Sedov solution, other evolutionary models, Coloumb equil., nonequilibrium ionization, cosmic ray shock acceleration
Binary X-ray sources: evidence for the black hole event horizon?
COGs (Clusters of Galaxies): Optical/X-ray classifications, luminosity functs, correlations, origin of Fe, Physical processes: sound speed, mean free paths, T equilibration timescales, heat conduction, convective stability, radiative cooling, X-ray structure, temp, binding masses, SZ effect, clusters as cosmological probes
AGN: Unified Scenario/Broad Fe lines
The address of this page is

Please send any comments to Jack Hughes, jph "at"

Revised March 11, 2011