Thesis defense [before December 2013]

Licentiate Thesis: Searching for Gamma Rays from Galaxy Clusters with the Fermi Large Area Telescope

Name: Licentiate Thesis: Searching for Gamma Rays from Galaxy Clusters with the Fermi Large Area Telescope
Start: 2013-11-14T13:15:00+01:00
End: 2013-11-14T15:00:00+01:00
Location: No location set

by Mr Stephan Zimmer (CoPS, Fermi-LAT)

Thursday 14 Nov 2013, 13:15 → 15:00 Europe/Stockholm

FA 32

Description

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 25% and associated limits on the maximum CR-to-thermal pressure ratio. 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 10^27 s over the mass range of 20 GeV– 2 TeV.