Searching for Gamma Rays from Galaxy Clusters with the Fermi Large Area Telescope: Cosmic Rays and Dark Matter
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
In this licentiate thesis, I report a search for GeV γ rays towards the location of Galaxy clusters. I mainly discuss the results of a search for cosmic-ray (CR) induced γ-ray emission but also briefly elaborate on a related study, searching for Dark Matter (DM)-induced γ-ray emission from Galaxy clusters. In addition, I provide a detailed discussion on the analysis tools that were used and discuss some additional tests that are not included in the papers this licentiate thesis is based on.
In a comprehensive search almost covering the entire sky, we find no statistically significant evidence for either DM or CR induced γ rays from galaxy clusters. Thus we report upper limits on CR quantities that exclude emission scenarios in which the maximum hadronic injection efficiency is larger than 21% and associated limits on the maximum CR-to-thermal pressure ratio, <XCR>. In addition, we update previous flux upper limits given a new set of modeling and taking the source extension into account. For a DM masses below 100 GeV, we exclude annihilation cross sections above ∼ 10−24 cm3 s−1 into bb. For decaying DM, we exclude decay times lower than 1027 s over the mass range of 20 GeV– 2 TeV.
Place, publisher, year, edition, pages
Stockholm: Stockholm University, 2013. , 57 p.
galaxy clusters, gamma rays, cosmic rays, dark matter, fermi-lat, likelihood analysis, joint likelihood
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-96231OAI: oai:DiVA.org:su-96231DiVA: diva2:665822
2013-11-14, FA 32, Albanova University Center, Fysikum, Stockholm University, 13:15 (English)
Clement, Christophe, Docent
List of papers