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Possible Evidence for Relativistic Shocks in Gamma-Ray BurstsRelativistic shock models of gamma-ray bursts may be tested by comparing their predicted low-energy asymptotic spectral indices s to observations. Synchrotron radiation theory predicts that the instantaneous spectrum has s = 1/3, and the spectrum integrated over the radiative decay of the electrons' energies has s = 1/2 with other cases lying between these limits. We examine the spectra of 11 bursts obtained by the Large Area Detectors on BATSE. One agrees with the predicted instantaneous spectrum, as does the initial portion of a second, and three are close to the predicted integrated spectrum. All of the observed asymptotic spectral slopes lie in the predicted range. This evidence for relativistic shocks is independent of detailed models of bursts and of assumptions about their distances. Radiation observed with the predicted instantaneous spectrum has a comparatively smooth time dependence, consistent with the necessarily long radiation time, while radiation observed with the predicted integrated spectrum has a spiky time dependence, consistent with the necessarily short radiation time.
Document ID
19990084089
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Cohen, E.
(Hebrew Univ. Jerusalem, Israel)
Katz, J. I.
(Washington Univ. Saint Louis, MO United States)
Piran, T.
(Hebrew Univ. Jerusalem, Israel)
Sari, R.
(Hebrew Univ. Jerusalem, Israel)
Preece, R. D.
(Alabama Univ. Huntsville, AL United States)
Band, D. L.
(California Univ., San Diego La Jolla, CA United States)
Date Acquired
August 19, 2013
Publication Date
October 10, 1997
Publication Information
Publication: Astrophysical Journal
Publisher: American Astronomical Society
Volume: 488
Issue: 1
Subject Category
Space Radiation
Funding Number(s)
CONTRACT_GRANT: NSF AST-94-16904
CONTRACT_GRANT: NAS8-36081
CONTRACT_GRANT: NAG3-516
CONTRACT_GRANT: NAG5-2682
Distribution Limits
Public
Copyright
Other

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