Ay 218 -Gamma Ray Astronomy

E.S. Phinney, T.A. Prince, S.R. Kulkarni

Gamma ray astronomy is entering a golden age, as new observatories such as GLAST (launch May 2008), HESS, VERITAS begin operation, and NuSTAR enters construction at Caltech. This seminar course is designed to expose students to the principles and prospects of the field. Topics will include detection and emission physics, techniques for obtaining multiwavlength observations, active galactic nuclei, blazars, pulsars, supernova remnants, cosmic rays, decaying cosmic particles, backgrounds and gamma-ray bursts.

Readings and class meeting dates:

1. April 2 Tom Prince: historical overview of the development of gamma-ray astronomy, instruments and satellite missions.
2. April 9 Sterl Phinney: review of gamma-ray emission processes and cross-sections and their importance in various astrophysical sources: inverse Comption, bremsstrahlung, synchrotron emission, particle production (electron-positron pair, pion) and annihilation, gamma rays from electromagnetic transitions between nuclear energy levels, and their excitation via 5-20 MeV particle collisions and via radioactive decay. Case study of the sad tale of the 30x expected ``discovery'' of excited gamma-ray emission from C, 0 in orion. COMPTEL observations of the Orion Complex by Bloemen et al 1994, and The Revised COMPTEL Orion results by Bloemen et al 1999.
3. April 16 , Tom Prince: Modern gamma-ray detectors (focus on GLAST and INTEGRAL): principles of operation, sensitivities, and spectral resolution.
4. April 23, Student shotgun lecture based on the following readings: Astrophysical constraints from gamma-ray spectroscopy by Diehl et al (2005 review article), overview and predictions by Renaud et al (2004), The Signature of 44Ti in Cassiopeia A Revealed by IBIS/ISGRI on INTEGRAL by Renaud et al (2006), Imaging the Gamma-Ray Sky with SPI aboard INTEGRAL by Knoediseder et al (2007), includes sky map in 26Al; Measuring 26Al and 60Fe in the Galaxy by Diehl (2006); SPI observations of the diffuse 60Fe emission in the Galaxy by W. Wang.
5. April 30, Student shotgun lecture based on the following two readings: [1] Weidenspointner et al. An asymmetric distribution of positrons in the Galactic disk revealed by gamma-rays (Nature 451, 159 (2008)). [2] Higdon, Lingenfelter and Rothschild The Galactic Positron Annihilation Radiation & the Propagation of Positrons in the Interstellar Medium. In addition to the above two readings, come prepared to discuss at least one of the following four papers: For serious discussions of the problems and possibilities with sources, see Guessoum, Jean and Prantzos Microquasars as sources of positron annihilation radiation and Prantzos On the intensity and spatial morphology of the 511keV emission in the Milky Way.. For laughs, you might like to look at Finkbeiner and Weiner Exciting Dark Matter and the INTEGRAL/SPI 511 keV signal and Boehm, Hooper, Silk and Casse MeV Dark Matter: Has it Been Detected?.
6. May 7 , No class.
7. May 14 , Student/Faculty-assisted lecture based on the following reading: Ribo TeV Gamma-Ray Astrophysics. When reading this, you are encouraged to follow up with supplementary reading in more depth on at least one of the topics of interest to you (i.e. how the instruments work, specific source results or specific source models). Particularly recommended are Weekes The Atmospheric Cherenkov Imaging Technique for Very High Energy Gamma-ray Astronomy [review of the showers and instrumental method], and on various sources, the following: Paredes VHE Gamma-rays from Galactic X-ray Binary Systems, Dubus Gamma-ray binaries: pulsars in disguise ?, Dubus et al The modulation of the gamma-ray emission from the binary LS 5039, Vannoni et al Diffusive Shock Acceleration in Radiation Dominated Environments, Bosch-Ramon et al Non-thermal emission from secondary pairs in close TeV binary systems, Reimer et al VHE gamma-rays from Westerlund 2 and implications for the inferred energetics, Funk VHE Gamma-ray supernova remnants, PuehlhoferUsing X-ray observations to identify the particle acceleration mechanisms in VHE SNRs and `dark' VHE sources.
8. May 21 , Fiona Harrison will lead a discussion of the technology and science of NuSTAR. Readings include the NuSTAR proposal science case (distributed via email), and the following readings on two examples of that science: nonthermal X-ray emission from clusters of galaxies, and atomic and nuclear lines in supernova remnants. Eckert et al INTEGRAL discovery of non-thermal hard X-ray emission from the Ophiuchus cluster, Petrosian et al Particle acceleration mechanisms (for nonthermal emission in cluster of galaxies), Nakar et al Cluster Merger Shock Constraints on Particle Acceleration and Nonthermal Pressure in the Intracluster Medium Vink X- and Gamma-ray Studies of Cas A: Exposing Core Collapse to the Core, Reynolds et al The Youngest Galactic Supernova Remnant: G1.9+0.3 (this is the new discovery Shri mentioned last week).
9. May 28 , GLAST. Readings: GLAST science brochure and GLAST science requirements document, and GLAST website. GLAST talks.

Last Update: 16 May, 2008