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UHECR Flux from SHDM Annihilation in GC-like Substructures

by Wunderle, Kai Erik

Abstract (Summary)
The objective of this thesis is to outline a relation between the measured Ultra High Energy Cosmic Ray (UHECR) flux and theoretical models for Super Heavy Dark Matter (SHDM) annihilation in Globular Cluster (GC)-like substructures in our Galaxy. Thus a possible solution for these two puzzling phenomena in present day astroparticle physics is presented.

A possible connection between GC-like substructures and UHECR sources was identified by combining the theoretical results for the annihilation of SHDM with the core densities derived from Dark Matter (DM)-profile fits to the GC data by Harris. The annihilation fluxes were derived for the Navarro, Frenk, and White-profile, the Moore-profile and a new constant density core approach. To compute the core densities of the GC-like substructures the GC-data by Harris were fitted to the most commonly used DM-profiles as well as to a more general DM-profile with variable inner power law index. The core densities were then calculated by making assumptions on the distribution of the masses in the GC-like substructure system as well as on the relation between the substructure mass and the core density.

Numerical simulations for the constant density core approach show that it is possible to reproduce the amount of substructure of the GC system of our Galaxy by choosing the mass fraction of the clumped dark matter to xi = 0.1 and the fraction of the heaviest substructure to eta = 0.01 xi, which corresponds to a mass of 10^9 M_odot for the most massive substructure. These simulation parameters then predict a product of the s-wave unitary bound with the fraction of the density of the Sun of zeta u approx 10^{-4}. Fits of the GC data to the DM-profiles reveal that all commonly used DM-profiles have to be rejected. Instead the profile with variable inner power law index is in good agreement with the GC data. The core densities are then calculated to range from 10^2 M_odot pc^{-3} to 10^8 M_odot pc^{-3}.

Therefore it can be concluded that SHDM annihilation in GC-like subclumps in our Galaxy presents a promising possibility to explain the measured UHECR flux.

Bibliographical Information:

Advisor:Xiao, Chijin; Tanaka, Kaori; Steele, Tom G.; Soteros, Chris; Manson, Alan; Dick, Rainer

School:University of Saskatchewan

School Location:Canada - Saskatchewan

Source Type:Master's Thesis

Keywords:uhecr shdm annihilation

ISBN:

Date of Publication:02/14/2006

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