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SAS-2 observations of the diffuse gamma radiation in the galactic latitude interval from 10 to 90 deg in both hemispheresAn analysis of all the second Small Astronomy Satellite (SAS-2) gamma-ray data for galactic latitudes higher than 10 deg in both hemispheres has shown that the intensity varies with galactic latitude, being larger near 10 deg than 90 deg. For energies above 100 MeV the gamma-ray data are consistent with a latitude distribution of the form I(b) = C1 + C2/sin b, with the second term being dominant. This result suggests that the radiation above 100 MeV is coming largely from local regions of the galactic disk. Between 35 and 100 MeV, a similar equation is also a good representation of the data, but here the two terms are comparable. These results indicate that the diffuse radiation above 35 MeV consists of two parts, one with a relatively hard galactic component and the other an isotropic steep spectral component which extrapolates back well to the low-energy (less than 10 MeV) diffuse radiation. The steepness of the diffuse isotropic component places significant constraints on possible theoretical models of this radiation.
Document ID
19770067738
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Fichtel, C. E.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Hartman, R. C.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Kniffen, D. A.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Thompson, D. J.
(NASA Goddard Space Flight Center Greenbelt, Md., United States)
Ogelman, H. B.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Ozel, M. E.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Tumer, T.
(Middle East Technical University Ankara, Turkey)
Date Acquired
August 9, 2013
Publication Date
October 1, 1977
Publication Information
Publication: Astrophysical Journal
Subject Category
Space Radiation
Accession Number
77A50590
Distribution Limits
Public
Copyright
Other

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