Observational cosmology with imperfect data

Bester, Hertzog Landman

Title: Observational cosmology with imperfect data
Creator: Bester, Hertzog Landman
ThesisAdvisor: Larena, Julien
ThesisAdvisor: Bishop, Nigel
Date: 2016
Type: Thesis
Type: Doctoral
Type: PhD
Identifier: http://hdl.handle.net/10962/463
Identifier: vital:19961
Description: We develop a formalism suitable to infer the background geometry of a general spherically symmetric dust universe directly from data on the past lightcone. This direct observational approach makes minimal assumptions about inaccessible parts of the Universe. The non-parametric and Bayesian framework we propose provides a very direct way to test one of the most fundamental underlying assumptions of concordance cosmology viz. the Copernican principle. We present the Copernicus algorithm for this purpose. By applying the algorithm to currently available data, we demonstrate that it is not yet possible to confirm or refute the validity of the Copernican principle within the proposed framework. This is followed by an investigation which aims to determine which future data will best be able to test the Copernican principle. Our results on simulated data suggest that, besides the need to improve the current data, it will be important to identify additional model independent observables for this purpose. The main difficulty with current data is their inability to constrain the value of the cosmological constant. We show how redshift drift data could be used to infer its value with minimal assumptions about the nature of the early Universe. We also discuss some alternative applications of the algorithm.
Format: 152 leaves, pdf
Publisher: Rhodes University, Faculty of Science, Mathematics (Pure and Applied)
Language: English
Rights: Bester, Hertzog Landman

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