In this thesis we place constraints on models of the late-time acceleration of the universe. We put constraints on DGP braneworld models using supernovae, the cosmic microwave background shift parameter, and the baryon oscillation peak in the SDSS luminous red galaxy sample. The flat self-accelerating DGP model is marginally allowed by the combined likelihood, but the standard Lambda COM model fits the data better. The best fit of the flat non-selfaccelerating DGP model corresponds to the LCDM limit, which therefore gives a slightly better fit to the data, having oi less parameter. However, there is still a region of non-LCDM parameter space allowed by observations. We then use Bayesian statistics to compare a set of general relativistic dark energy models with a set of DGP models. Using Hubble rate data from differential iges of galaxies, combined with other background tests, we find that the flat self-accelerating DGP model is strongly disfavoured with respect to the flat LCDM model, and that braneworld models are generally disfavoured. We also show that all the models with more than two parameters are poorly constrained.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:494017 |
| Date | January 2008 |
| Creators | Majerotto, Elisabetta |
| Publisher | University of Portsmouth |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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