In this dissertation, we consider the variable chaplygin gas (VCG) model as derived
from the Tachyon gas model and search for a sub-class of models that provide an
adequate fit to the cosmic microwave background (CMB) observations. We find
that, for an appropriate choice of VCG parameters, up to ~ 80% of the VCG
collapses into a gravitationally bound condensate which behaves as matter; the
evolution of the remaining VCG, as governed by its equation of state, brings about
accelerated expansion at late times. In light of this high collapsed fraction, we
approximate the VCG transfer function with that of cold dark matter. We show
that we can sufficiently describe the VCG cosmology from decoupling to today in
terms of a model in which the gravitationally bound condensate plays the role of
cold dark matter and the remaining VCG takes the place of dark energy in the
concordance model. We then compute the CMB temperature anisotropy spectrum
for a subset of VCG models and proceed to find a best-fit model to the WMAP-9yr
data [46]. Our best-fit model has a x² per degrees of freedom of 2.03. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/9206 |
| Date | January 2013 |
| Creators | Makhathini, Sphesihle. |
| Contributors | Zunckel, Caroline. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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