Diffuse extragalactic background radiation

Joel R. Primack, Rudy C. Gilmore, Rachel S. Somerville

Research output: Contribution to journalConference articlepeer-review

29 Scopus citations


Attenuation of high-energy gamma rays by pair-production with UV, optical and IR background photons provides a link between the history of galaxy formation and high-energy astrophysics. We present results from our latest semi-analytic models (SAMs), based upon a ACDM hierachical structural formation scenario and employing all ingredients thought to be important to galaxy formation and evolution, as well as reprocessing of starlight by dust to mid- and far-IR wavelengths. Our models also use results from recent hydrodynamic galaxy merger simulations. These latest SAMs are successful in reproducing a large variety of observational constraints such as number counts, luminosity and mass functions, and color bimodality. We have created 2 models that bracket the likely ranges of galaxy emissivities, and for each of these we show how the optical depth from pair-production is affected by redshift and gamma-ray energy. We conclude with a discussion of the implications of our work, and how the burgeoning science of gamma-ray astronomy will continue to help constrain cosmology.

Original languageEnglish (US)
Pages (from-to)71-82
Number of pages12
JournalAIP Conference Proceedings
StatePublished - 2009
Externally publishedYes
Event4th International Meeting on High Energy Gamma-Ray Astronomy - Heidelberg, Germany
Duration: Jul 7 2008Jul 11 2008

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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