University of Hertfordshire

From the same journal

From the same journal

Fermi Large Area Telescope Constraints on the Gamma-ray

Research output: Contribution to journalArticlepeer-review

Documents

  • A.A. Abdo
  • M. Ackermann
  • M. Ajello
  • A. Allafort
  • W.B. Atwood
  • L. Baldini
  • J. Ballet
  • J. Granot
  • M. Ziegler
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Original languageEnglish
Pages (from-to)1082-1096
JournalThe Astrophysical Journal
Volume723
Issue2
Publication statusPublished - 2010

Abstract

The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts (GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of gamma-ray flux attenuation by the EBL. We place upper limits on the gamma-ray opacity of the Universe at various energies and redshifts, and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. (2006) can be ruled out with high confidence.

Notes

‘In these times, during the rise in the popularity of institutional repositories, the Society does not forbid authors from depositing their work in such repositories. However, the AAS regards the deposit of scholarly work in such repositories to be a decision of the individual scholar, as long as the individual's actions respect the diligence of the journals and their reviewers.’ Original article can be found at: http://iopscience.iop.org/ Copyright American Astronomical Society

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