In this thesis I examine some extensions to the concordance model of cosmology and their observational consequences. In particular, I look at how vector perturbations sourced by cosmic strings could generate a B-mode signal in weak lensing surveys. For a string network close to the current observational upper bound, this signal could be detected within the next 5-10 years. I also examine model independent modified gravity and forecast the constraints that could be obtained with the combination CMB+weak lensing+galaxy cluster counts. For the specific example of Planck (CMB+cluster catalogue) and DES(weak lensing), deviations from General Relativity could be constrained to within 5% in the next 3-4 years. The forecast for cluster counts relies on mass functions calibrated for ∧CDM+GR cosmologies, so I then investigate how reliable the predictions are in the case of modified gravity. At first glance, it appears that the mass function formalism is reliable and, with a little cheating, can even work in the case where modified gravity has a screening scale.
Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:560624 |
Date | January 2012 |
Creators | Thomas, Daniel |
Contributors | Contaldi, Carlo |
Publisher | Imperial College London |
Source Sets | Ethos UK |
Detected Language | English |
Type | Electronic Thesis or Dissertation |
Source | http://hdl.handle.net/10044/1/9825 |
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