All the natural electromagnetic radiation reaching the Earth, whether from nearby or remote parts of the universe, brings with it information on the contents or structure of the region in which it originated. This is true of each part of the spectrum, from radio waves through the visible, ultraviolet and x‐ray regions, to the realm of high‐energy gamma rays which is our subject here. We will be concentrating on celestial gamma rays, with energies above about 10 MeV, which provide clear and in some respects unique information on the high‐energy particles and processes in the universe, both currently and in the remote past.
REFERENCES
1.
W. L.
Kraushaar
, G. W.
Clark
, G. P.
Garmire
, R.
Borken
, P.
Higbie
, V.
Leong
, T.
Thorsos
, Ap. J.
177
, 341
(1972
).2.
S. M.
Derdeyn
, C. H.
Ehrmann
, C. E.
Fichtel
, D. A.
Kniffen
, R. W.
Ross
, Nucl. Instr. and Meth.
98
, 557
(1972
).3.
P.
Albats
, S. E.
Ball
, J. P.
Delvaille
, K. I.
Greisen
, D. G.
Koch
, B.
McBreen
, G. G.
Fazio
, D. R.
Hearn
, Nucl. Instr. and Meth.
95
, 189
(1971
).4.
G. G.
Fazio
, D. R.
Hearn
, H. F.
Helmken
, G. H.
Rieke
, T. C.
Weekes
, Acta Phys.
29
, Supl. 1
, 111
(1970
).5.
6.
7.
8.
K. Greisen, Perspectives in Modern Physics (R. W. Marshak, ed.), Interscience, New York, (1966); page 355.
9.
10.
D. A. Kniffen, Appendix to Cosmic Gamma Rays, NASA SP 249 (by F. E. Stecker), GPO, Washington, D.C. (1971); page 225.
11.
C. E. Fichtel, “Techniques for Gamma Rays,” in IAU Symposium No. 41 on New Techniques in Space Astronomy (1970).
12.
D. A.
Kniffen
, R. C.
Hartman
, D. J.
Thompson
, C. E.
Fichtel
, Ap. J. Lett.
186
, L105
(1973
).13.
C. E.
Fichtel
, R. C.
Hartman
, D. A.
Kniffen
, D. J.
Thompson
, G. F.
Bignami
, H.
Ögelman
, M. F.
Ozel
, T.
Tümer
, Ap. J.
198
, 163
(1975
).14.
S. C. Simonson III, “Density‐Wave Map of the Galactic Spiral Structure,” Univ. of Md. preprint (1973).
15.
D. J.
Thompson
, G. F.
Bignami
, C. E.
Fichtel
, D. A.
Kniffen
, Ap. J. Lett.
190
, L51
(1974
).16.
D. J. Thompson, C. E. Fichtel, D. A. Kniffen, H. Ogelman, Ap. J. Lett. (to be published in September 1975).
17.
18.
19.
20.
21.
22.
23.
G. F.
Bignami
, C. E.
Fichtel
, D. A.
Kniffen
, D. J.
Thompson
, “High Energy Galactic Gamma Radiation from Cosmic Rays Concentrated in Spiral Arms
,” Ap. J. Lett.
199
(in press, 1975
).24.
F. W.
Stecker
, P. M.
Solomon
, N. Z.
Scoville
, C. E.
Ryter
, “Molecular Hydrogen in the Galaxy and Galactic γ‐Rays
,” Ap. J.
201
(in press, 1975
).25.
26.
See reference 13 and references contained therein.
27.
F. W.
Stecker
, D. L.
Morgan
, J.
Bredekamp
, Phys. Rev. Lett.
27
, 1469
(1971
).28.
D. Schwartz, H. Gursky in Gamma Ray Astrophysics (F. W. Stecker, J. I. Trombka, eds.), GPO, Washington, D.C. (1973).
29.
30.
D. A.
Kniffen
, R. C.
Hartman
, D. J.
Thompson
, G. F.
Bignami
, C. E.
Fichtel
, H.
Ögelman
, T.
Türner
, Nature
251
, 397
(1974
), and references contained therein.31.
G. G. Fazio, H. F. Helmken, G. H. Rieke, T. C. Weekes, IAU Symposium No. 37 on Non‐Solar X‐ and Gamma‐Ray Astronomy (1969).
32.
K.
Greisen
, S. E.
Ball
Jr, M.
Campbell
, D.
Gilman
, M.
Strickman
, B.
McBreen
, D.
Koch
, Ap. J.
197
, 471
(1975
).33.
P.
Albats
, G. M.
Frye
Jr, G. B.
Thomson
, V. D.
Hopper
, O. B.
Mace
, J. A.
Thomas
, J. A.
Staib
, Nature
251
, 500
(1974
).34.
35.
This content is only available via PDF.
© 1975 American Institute of Physics.
1975
American Institute of Physics
You do not currently have access to this content.
