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Aspects of cosmic structure formation in coupled scalar field dark matter models

Beyer, Joschka Johannes

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Abstract

In this thesis we introduce a novel coupled two scalar field model of the dark sector motivated by higher dimensional dilatation symmetric theories of gravity, which could potentially provide a solution to the cosmological constant problem. This work is split up into four parts. First, we motivate the model and discuss its evolution at the background level. We find a quintessence-type scaling solution in the early universe and a coupled cold dark matter scenario for later times. At the level of linear perturbations we introduce an effective fluid description of this model and implement it into a Boltzmann-code to recover the linear power spectrum, which exhibits a characteristic suppression of power at a Jeans scale. In a third step we analyze superhorizon perturbations in the early universe in some detail, with particular focus on the issue of the stability of the adiabatic perturbation mode. Finally we apply the extended Press-Schechter formalism to predict substructure abundances within a typical galaxy like the Milky Way and use the results to obtain parameter bounds for our model.

Item Type: Dissertation
Supervisor: Wetterich, Prof. Dr. Christof
Date of thesis defense: 29 October 2014
Date Deposited: 06 Nov 2014 10:41
Date: 2014
Faculties / Institutes: The Faculty of Physics and Astronomy > Institute for Theoretical Physics
Subjects: 500 Natural sciences and mathematics
530 Physics
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