Population Studies of Unidentified High-Energy Gamma-Ray Sources

  • Neil Gehrels
  • Daryl J. Macomb
  • David L. Bertsch
  • David J. Thompson
  • Robert C. Hartman
  • Barbara J. Mattson
Conference paper
Part of the Astrophysics and Space Science Library book series (ASSL, volume 267)

Abstract

The third EGRET catalog contains ~ 170 unidentified high energy gamma-ray point sources. Here we report that this group contains two populations with different spatial distributions, flux distributions and spectral properties. A cluster of ~ 20 sources lies just north of the Galactic Center and is part of a larger population of faint objects at mid-latitudes. We show that these mid-latitude sources are distinct from the population of bright sources found at lower latitudes. The spatial distribution of the mid-latitude population suggests a Gould belt origin.

Keywords

Gamma-ray: observations Gamma-ray sources: unidentified 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Dixon, D. D. et al. (1998)New Astronomy, 3, 539ADSCrossRefGoogle Scholar
  2. Esposito, J. A. et al. (1996)ApJ, 461, 820ADSCrossRefGoogle Scholar
  3. Gehrels, N., Michelson, P. (1999)Astroparticle Physics, 11, 277ADSCrossRefGoogle Scholar
  4. Gehrels, N., Macomb, D. J., Bertsch, D. L., Thompson, D. J., Hartman, R. C. (2000)Nature, 404, 363ADSCrossRefGoogle Scholar
  5. Grenier, I. A., Perrot, C. (1999)Proc. XXVIInt. Cosmic Ray Conf. Salt Lake City, 3, 476Google Scholar
  6. Guillout et al. (1998)A&A, 337, 113ADSGoogle Scholar
  7. Hartman, R.C., et al. (1999)ApJS, 123, 79ADSCrossRefGoogle Scholar
  8. Houston, B. P.,Wolfendale, A. W. (1983)A&A, 126, 22ADSGoogle Scholar
  9. Hunter, S. D. et al. (1997)ApJ, 481, 205ADSCrossRefGoogle Scholar
  10. Kaaret, P., Cottam, J. (1996)ApJ, 462, L35ADSCrossRefGoogle Scholar
  11. Lindblad, P. 0., Grupe, K., Sandqvist, Aa.,Schuber, J. (1973)APIA, 24, L309Google Scholar
  12. Montmerle, T. (1979)ApJ, 231, 95ADSCrossRefGoogle Scholar
  13. Olano, C. A. (1982)A&A, 112, 195ADSGoogle Scholar
  14. Romani, R. W., Yadigaroglu, I.-A. (1995)ApJ, 438, 314ADSCrossRefGoogle Scholar
  15. Romero, G. E., Benaglia, P. & Torres, D. F. (1999)A&A, 348, 868ADSGoogle Scholar
  16. Stothers, R. & Frogel, J. A. (1974)AJ, 79, 456ADSCrossRefGoogle Scholar
  17. Sturner, S. J. & Dermer C. D. (1995)APIA, 293, L17Google Scholar
  18. Swanenburg, B. N. et al. (1981)ApJ, 243, L69ADSCrossRefGoogle Scholar
  19. Taylor, D. K., Dickman, R. L., Scoville, N. Z. (1987)ApJ, 315, 104 Thompson, D. J. et al. (1994)ApJ, 436, 229Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2001

Authors and Affiliations

  • Neil Gehrels
    • 1
    • 2
  • Daryl J. Macomb
    • 1
    • 2
  • David L. Bertsch
    • 1
    • 2
  • David J. Thompson
    • 1
    • 2
  • Robert C. Hartman
    • 1
    • 2
  • Barbara J. Mattson
    • 1
    • 3
  1. 1.NASA/Goddard Space Flight CenterGreenbeltUSA
  2. 2.Universities Space Research AssociationLanhamUSA
  3. 3.Emergent Information Technologies Inc.ClintonUSA

Personalised recommendations