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High-energy gamma radiation from Geminga observed by EGRETThe Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) has carried out extensive studies of the gamma-ray source Geminga. Following the detection of pulsed X-rays (Halpern and Holt 1992) from Geminga, Bertsch et al. (1992) reported the same 237 ms periodicity to be visible in the EGRET data. A full analysis of the Geminga source shows that the energy spectrum is compatible with a power law with a spectral index of -1.50 +/- 0.08 between 30 MeV and 2 GeV. A falloff relative to the power law is observed for energies above 2 GeV. Phase-resolved spectra also show power laws with high-energy cutoffs, but with significant variation of the spectral index with phase. No unpulsed emission is observed. No evidence for time variation was found within the EGRET observations.
Document ID
19950035685
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Mayer-Hasselwander, H. A.
(Max-Planck-Institut fuer extraterrestrische Physik Garching, Germany)
Bertsch, D. L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Brazier, K. T. S.
(Max-Planck-Institut fuer extraterrestrische Physik Garching, Germany)
Chiang, J.
(Stanford University Stanford, CA, United States)
Fichtel, C. E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Fierro, J. M.
(Stanford University Stanford, CA, United States)
Hartman, R. C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hunter, S. D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kanbach, G.
(Max-Planck-Institut fuer extraterrestrische Physik Garching, Germany)
Kwok, P. W.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 16, 2013
Publication Date
January 20, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 421
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A67284
Funding Number(s)
CONTRACT_GRANT: NAG5-1605
CONTRACT_GRANT: NAS5-31210
CONTRACT_GRANT: NAG5-1742
Distribution Limits
Public
Copyright
Other

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