J-factors of Dwarf Spheroidal Galaxies with Self-Interacting Dark Matter

Examensarbete för kandidatexamen

Please use this identifier to cite or link to this item: https://hdl.handle.net/20.500.12380/256432
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Type: Examensarbete för kandidatexamen
Bachelor Thesis
Title: J-factors of Dwarf Spheroidal Galaxies with Self-Interacting Dark Matter
Authors: Eriksson, Magdalena
Eurenius, Björn
Larsson, Susanna
Wadman, Rikard
Abstract: Most of the matter in the Universe is unidentified and invisible, i.e. dark. Detecting dark matter particles from the Cosmos is arguably one of the most pressing research questions in science today. In the standard paradigm of modern cosmology, dark matter is assumed to consist of weakly interacting massive particles, which may annihilate in pairs into gamma photons. Such annihilations give rise to a measurable gamma ray flux, the amplitude of which is proportional to a so-called J-factor. Current J-factor calculations usually neglect dark matter self-interactions. However, dark matter self-interactions are compatible with current astrophysical observations, and can potentially solve long-standing problems regarding the formation and evolution of galaxies. The purpose of this thesis is to perform the first self-consistent J-factor calculation which includes dark matter self-interactions. This calculation is based upon the combined use of nonrelativistic quantum mechanics and Newtonian galactic dynamics. The formalism developed in this thesis has been applied to a sample of 20 dwarf spheroidal galaxies, which are known to be dark matter dominated astrophysical objects. For each galaxy in the sample, a likelihood analysis based on actual stellar velocity data has been performed in order to extract the distribution of dark matter in the galaxy, and estimate the induced error on the associated J-factor. We have found that the J-factors for self-interacting dark matter can be larger than standard J-factors by several orders of magnitude. Previous attempts to include dark matter self-interactions in the J-factor calculation neglect the details of the dark matter distribution in dwarf spheroidal galaxies. We have shown that this approximation leads to relative errors on the J-factors as large as two orders of magnitude. A paper illustrating these results is currently in preparation and is to be submitted to JCAP (impact factor 5.634).
Keywords: Fysik;Physical Sciences
Issue Date: 2017
Publisher: Chalmers tekniska högskola / Institutionen för fysik (GU)
Chalmers University of Technology / Department of Physics (GU)
URI: https://hdl.handle.net/20.500.12380/256432
Collection:Examensarbeten för kandidatexamen // Bachelor Theses

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