Brown, S (2022) The Cosmological Dependence of the Formation and Evolution of Dark Matter Haloes. Doctoral thesis, Liverpool John Moores University.

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Abstract

Over the past few decades numerical simulations with collisionless dynamics have reached a consensus about the form of the internal structure of dark matter (DM) haloes. However, the theoretical origin of these is still poorly understood. In this thesis I focus on studying the link between the initial primordial power density fluctuations and the internal structure of collapsed DM haloes today. This is the main focus of this thesis, and is split into three main parts; in the first chapter I study the dependence of the internal properties of DM haloes, primarily the mass density and pseudo phase space density (PPSD) profiles, on initial density fluctuation by systematically varying both the amplitude and slope of the linear power spectrum. It is observed that a number of previously assumed universal results break down when the initial power spectrum deviates from the CMB normalised case with the density profiled deviating strongly from an NFW form, with steeper slopes than −3, and the PPSD power law slope now exhibiting a clear cosmological dependence. In the second part of this thesis the simulations introduced in the first section are used to develop a model to predict the density profiles of DM haloes for a general mass, redshift and cosmology. To fully describe the density profiles observed in simulations two parameters are required: concentration, c, and an additional ‘shape’ parameter, α. I demonstrate that these two parameters can be expressed as a single, universal function of peak height using an appropriately chosen window function, allowing for a simple model to be developed. In the final section of this thesis I explore the joint effects of warm dark matter (WDM) and baryonic effects on the satellite populations of Milky Way mass systems. Here it is found that there is a strong degeneracy between the feedback (subgrid) parameters and the assumed WDM strength that should be taken into account when placing constraints on WDM and similar cosmological extensions.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Cosmology; Galaxy Formation
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
SWORD Depositor:	A Symplectic
Date Deposited:	26 Aug 2022 08:39
Last Modified:	26 Aug 2022 08:40
DOI or ID number:	10.24377/LJMU.t.00017445
Supervisors:	McCarthy, Ian and Font, Andreea
URI:	https://researchonline.ljmu.ac.uk/id/eprint/17445

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