On the evolution of large-scale structure in a cosmic void

dc.contributor.advisorClarkson, Chrisen_ZA
dc.contributor.advisorEllis, GFRen_ZA
dc.contributor.authorFebruary, Sean Phillipen_ZA
dc.date.accessioned2014-10-21T13:45:40Z
dc.date.available2014-10-21T13:45:40Z
dc.date.issued2014en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractFuture large-scale structure surveys are expected to pin-down the properties of dark energy significantly more by mapping the cosmic web to unprecedented precision. To take advantage of such state-of-the-art technologies, the evermore accurate modelling of structure formation is absolutely necessary. While relativistic linear and non-relativistic (Newtonian) non-linear effects have been well established (although improvements are still being made), a fairly unexplored area is the impact of relativistic, non-linear effects on structure formation. As an attempt in this direction, we consider linear perturbations of a Lemaître-Tolman-Bondi (LTB) spacetime. LTB models are spherically symmetric but inhomogeneous exact dust solutions to the Einstein field equations. They are known to accommodate most observations of the background universe without dark energy. In this work we present a new numerical code to solve the set of coupled partial differential equations that describe the evolution of the (polar) perturbations, test it in the case of a Hubble-scale LTB void, and demonstrate its excellent stability and convergence. We then explore the solutions for a variety of generic initial conditions. The variable that closely resembles the Newtonian potential is shown to excite propagating (tensor) as well as rotational (vector) modes at the percent-level. Comparing our results to that which ignores the full coupling, we estimate percent-level corrections to the amplitude of the galaxy correlation function when only the scalar degrees of freedom are included. In addition, we showed that the anisotropic correlation function can nevertheless be used as a test of the Copernican Principle. Note that our code has applications to other scenarios as well in which spherical symmetry is a good approximation, such as the lensing of gravitational waves by intervening halos/voids.en_ZA
dc.identifier.apacitationFebruary, S. P. (2014). <i>On the evolution of large-scale structure in a cosmic void</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Mathematics and Applied Mathematics. Retrieved from http://hdl.handle.net/11427/8698en_ZA
dc.identifier.chicagocitationFebruary, Sean Phillip. <i>"On the evolution of large-scale structure in a cosmic void."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Mathematics and Applied Mathematics, 2014. http://hdl.handle.net/11427/8698en_ZA
dc.identifier.citationFebruary, S. 2014. On the evolution of large-scale structure in a cosmic void. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - February, Sean Phillip AB - Future large-scale structure surveys are expected to pin-down the properties of dark energy significantly more by mapping the cosmic web to unprecedented precision. To take advantage of such state-of-the-art technologies, the evermore accurate modelling of structure formation is absolutely necessary. While relativistic linear and non-relativistic (Newtonian) non-linear effects have been well established (although improvements are still being made), a fairly unexplored area is the impact of relativistic, non-linear effects on structure formation. As an attempt in this direction, we consider linear perturbations of a Lemaître-Tolman-Bondi (LTB) spacetime. LTB models are spherically symmetric but inhomogeneous exact dust solutions to the Einstein field equations. They are known to accommodate most observations of the background universe without dark energy. In this work we present a new numerical code to solve the set of coupled partial differential equations that describe the evolution of the (polar) perturbations, test it in the case of a Hubble-scale LTB void, and demonstrate its excellent stability and convergence. We then explore the solutions for a variety of generic initial conditions. The variable that closely resembles the Newtonian potential is shown to excite propagating (tensor) as well as rotational (vector) modes at the percent-level. Comparing our results to that which ignores the full coupling, we estimate percent-level corrections to the amplitude of the galaxy correlation function when only the scalar degrees of freedom are included. In addition, we showed that the anisotropic correlation function can nevertheless be used as a test of the Copernican Principle. Note that our code has applications to other scenarios as well in which spherical symmetry is a good approximation, such as the lensing of gravitational waves by intervening halos/voids. DA - 2014 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2014 T1 - On the evolution of large-scale structure in a cosmic void TI - On the evolution of large-scale structure in a cosmic void UR - http://hdl.handle.net/11427/8698 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/8698
dc.identifier.vancouvercitationFebruary SP. On the evolution of large-scale structure in a cosmic void. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Mathematics and Applied Mathematics, 2014 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/8698en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Mathematics and Applied Mathematicsen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.titleOn the evolution of large-scale structure in a cosmic voiden_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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