Phd Thesis defense: Searching for dark matter in the Galactic Halo with IceCube using high energy cascades
Monday 12 June 2017
to 17:00 at
Samuel Flis (Stockholm University, Department of Physics)
The presence of dark matter is inferred at scales ranging from rotations of galaxies to imprints in the CMB – the Big Bang
after-glow. The nature of dark matter is, however, still unknown as no detection other than the gravitational one has been
made. This thesis presents two analyses searching for a neutrino signal from dark matter annihilations in the Milky Way.
The first analysis searched for an excess of νμ charged current events with directions from the central region of the dark
matter halo and, was focused on low energy events, thus probing low dark matter particle masses. Approximately 319 days
of data collected with the 79-string configuration of the IceCube detector was used in the analysis. Despite a large deficit in
the number of observed events the data were found to be consistent with background and upper limits were set on <σⱴ>. At
the time of the analysis these limits were the strongest set by a neutrino experiment below 100 GeV.
The second analysis was performed on a data sample originally used in an unfolding analysis of the atmospheric and
astrophysical neutrino spectra. The data consisted of contained cascade events above 1 TeV collected with the 79-string
configuration and the completed detector in the 86-string configuration during two years of data-taking. The limits set
by this analysis were more constraining by up to a factor of 10 compared to previous IceCube analyses, and the most
competitive limits are set assuming a Burkert halo profile. These two analyses prompted the development of a signal
subtraction likelihood method to address the problem of signal contamination in background estimates based on scrambled
Additionally a study concerning future extensions of IceCube in the Gen2 project is presented. The cascade
reconstruction performance was examined and compared for different proposed detector extensions.