Contribution to the extragalactic gamma-ray background from discrete sources

D. Bhattacharya, P. Sreekumar, R. Mukherjee

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The extragalactic gamma ray background (EGRB) could arise from two distinct scenarios: truly diffuse processes or from unresolved point sources. Here we examine contribution from unresolved normal galaxies, starburst galaxies and AGNs. γ-ray emission from normal galaxies is mostly due to cosmic ray interactions with interstellar matter and radiation. Though no starburst galaxy has been detected so far in γ-rays, enhanced supernovae activity is expected to lead to higher cosmic ray densities, making starburst galaxies sufficiently γ-ray luminous to be detected by GLAST, γ-rays from blazars are believed to arise from relativistic jets. The γ-ray emission is expected to decrease with increasing jet inclination angle. The γ-ray detection of Cen A and NGC 6251 suggests, other sub-classes of AGNs could also be potential contributors to the γ-ray background. Preliminary results are discussed.

Original languageEnglish
Title of host publicationFirst GLAST Symposium
Number of pages2
Publication statusPublished - 2007
Event1st Gamma-ray Large Area Space Telescope Symposium, GLAST - Stanford, CA, United States
Duration: 05-02-200708-02-2007


Conference1st Gamma-ray Large Area Space Telescope Symposium, GLAST
Country/TerritoryUnited States
CityStanford, CA

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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