Hostname: page-component-77c89778f8-gvh9x Total loading time: 0 Render date: 2024-07-21T17:30:25.710Z Has data issue: false hasContentIssue false
  • English
  • Français

Possible initial evidence of extragalactic cosmic-ray protons and the age of extragalactic cosmic-ray sources

Published online by Cambridge University Press:  14 August 2015

F. W. Stecker
F. W. Stecker*
Affiliation:
Theoretical Studies Branch, NASA Goddard Space Flight Center, Greenbelt, Md., U.S.A.

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

We have compared the recent cosmic background γ-ray observations with spectra predicted by various possible cosmic interactions. We find that the observed isotropic γ-rays with energies > 1 MeV can best be explained as being due to the decay of π°-mesons produced in extra-galactic cosmic-ray collisions. This interpretation indicates that extragalactic cosmic-ray sources were more active (or prevalent) in the past and started to form at a redshift of ∼ 100 corresponding to 107–108 years after the ‘big-bang’.

For a present extragalactic gas density of 10−7–10−5 cm−3, the present extragalactic cosmic-ray flux is inferred to be 10−5–10−3 the galactic value.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 37: Non-Solar X- and Gamma-Ray Astronomy , 1970 , pp. 382 - 384
Copyright
Copyright © Reidel 1970 

References

[1] Stecker, F. W.: 1968, Nature 220, 675; Corrections: Nature 222, 1157 (1969).Google Scholar
[2] Stecker, F. W.: 1969, Nature 221, 425; Corrections: Nature 222, 1157 (1969).Google Scholar
[3] Stecker, F. W.: 1969, Astrophys. J. 157, 507.Google Scholar
[4] Stecker, F. W. and Silk, J.: 1969, Nature 221, 1229.Google Scholar
[5] Felten, J. E. and Morrison, P.: 1966, Astrophys. J. 146, 686.Google Scholar
Fazio, G. G., Stecker, F. W., and Wright, J. P.: 1966, Astrophys. J. 144, 611.CrossRefGoogle Scholar
Gould, R. J.: 1965, Phys. Rev. Letters 15, 511.Google Scholar
Hoyle, F.: 1965, Monthly Notices Roy. Astron. Soc. 120, 338 Google Scholar
[6] Silk, J. and McCray, R.: 1969, Astrophys. Letters 3, 59.Google Scholar
[7] Brecher, K. and Morrison, P.: 1969, Astrophys. J. Letters 150, L61.Google Scholar
[8] Clark, G. W., Garmire, G. P., and Kraushaar, W. L.: 1968, Astrophys. J. Letters 153, L203.Google Scholar
[9] Vette, J. I., Gruber, D., Matteson, J. L., and Peterson, L. E.: 1970, this volume, p. 335.Google Scholar
[10] Metzger, A. E., Anderson, E. C., van Dilla, M. A., and Arnold, J. R.: 1964, Nature 204, 766.Google Scholar
[11] See, for example, References in Gould, R. J.: 1967, Am. J. Phys. 35, 376.Google Scholar
[12] Weymann, R.: 1967, Astrophys. J. 147, 887.Google Scholar
[13] Longair, M. S.: 1966, Monthly Notices Roy. Astron. Soc. 133, 421.Google Scholar
Rowan-Robinson, M.: 1968, Monthly Notices Roy. Astron. Soc. 138, 445.Google Scholar
Schmidt, M.: 1968, Astrophys. J. 151, 393.Google Scholar
[14] Bergamini, R., Londrillo, P., and Setti, G.: 1967, Nuovo Cimento 52B, 495.Google Scholar
[15] See discussion and references in Ginzburg, V. L.: 1968, Astrophys. Space Sci. 1, 125.Google Scholar