Allen D. Zych
Professor of Physics
Chair of the Department of Physics
Ph.D., 1968, Case Western Reserve
M.S., 1965, Case Institute of Technology
B.S., 1961, Case Institute of Technology

Space physics and astrophysics; atmospheric and solar neutron sources; celestial gamma-ray sources.

Office: 3041 Physics Building
Voice: (909) 787-5642
Fax: (909) 787-4529


Historically, the high energy astrophysics (HEA) research program at the University of California, Riverside (UCR) has been focused on the technological development and application of Compton telescopes for intermediate energy (0.3-30 MeV) gamma-ray astronomy. In this energy range, Compton scattering is the dominant photon interaction process with the photoelectric and pair processes dominating at lower and higher energies, respectively. This energy range is also where many distant Active Galactic Nuclei (AGN) emit most of their radiation. The question of "how" accreting matter on a massive black hole in the early universe converts gravitational potential energy to produces most of its radiation as energetic gamma rays is a central problem today in astrophysics. Also, why is the gamma-ray emissions from Seyfert galaxies, quasars, B-Lac objects, blazars and radio galaxies different and how do these AGNs evolve into our present nearby universe?

We are now developing a new instrument concept for possible future space applications called the "Tracking and Imaging Gamma-Ray Experiment (TIGRE)". There is a growing consensus among gamma-ray astronomers that an improved Compton telescope will be the instrument of choice for low/medium energy gamma-ray observations in the next millennium. It will have the improved energy and angular resolutions, sensitivity and wide field-of-view to bridge the "gap" between x-ray and high energy gamma-ray astronomy.

NASA's Compton Gamma-Ray Observatory (CGRO) was launched into space in 1990. The CGRO has four separate instruments covering the gamma-ray energy range from 20 keV to 20 GeV. These are the BATSE, OSSE, COMPTEL and EGRET instruments. The CGRO Guest Investigator program has given us access to newly acquired space-based data for all four instruments. New imaging tools have been developed at UCR to detect fainter gamma-ray sources. These analyses will continue to produce exciting new results for many years.

imageSelected Publications

Akyüz, A., D. Bhattacharya, D. D. Dixon, T. J. O'Neill, O. T. Tümer, R. S. White, and A. D. Zych, "Polarization Measurements With An Imaging Gamma-ray Telescope", Experimental Astronomy 6, 275-284 (1995).

Akyüz, A., D. Bhattacharya, K. W. Chuang, D. D. Dixon, T. J. O'Neill, O. T. Tümer, R. S. White and A. D. Zych, "Atmospheric Gamma Rays at Geomagnetic Latitudes of -29o and +43o", J. Geophysical . Res. 102, No. A8, 17,359-17,364 (1997).

Jaffe, T. R., D. Bhattacharya, D. D. Dixon and A. D. Zych, "Evidence for Extended High Energy γ- Ray Emission from the Rosette/Monoceros Region", Astrophysical Journal Letters 384, L129-L131 (1997).

T. J. O'Neill, A. Akyüz, D. Bhattacharya, J. Samimi and A. Zych, "The TIGRE Gamma-Ray Telescope", Gamma-Ray Astrophysics 2001, edited by S. Ritz, N. Gehrels and C. Shrader, AIP Conference Proceedings 587, 882-886 (2001).

D. Bhattacharya, A. Akyüz, T. Miyagi, and A. Zych, "Galactic Plane EGRET Unidentified Source", Gamma-Ray Astrophysics 2001, edited by S. Ritz, N. Gehrels and C. Shrader, AIP Conference Proceedings 587, 683-687 (2001). 


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