Constraining non-standard cosmological models

Current observational evidence does not yet exclude the possibility that dark energy could be in the form of phantom energy. A universe consisting of a phantom constituent will be driven toward a drastic end known as the `Big Rip' singularity where all the matter in the universe will be destroyed. Motivated by this possibility, other evolutionary scenarios have been explored by e.g. Barrow, including the phenomena which he called Sudden Future Singularities (SFS). In a model consisting of such events it is possible to have a blow up of the pressure occurring at sometime in the future evolution of the universe while the energy density would remain unaffected. The particular evolution of the scale factor of the universe in this model that results in a singular behaviour of the pressure also admits acceleration in the current era. In this thesis we will present the results of our confrontation of one example class of SFS models with the available cosmological data from high redshift supernovae, baryon acoustic oscillations (BAO) and the cosmic microwave background (CMB). We then discuss the viability of the model under consideration in light of the data.\\ More importantly however in this pursuit, we will make the case that the cosmological constraints employed in this analysis were not blindly applied to the non-standard model in question, which is not unfortunately the practice that is always followed in the cosmology community. This applicability issue is a very important one which if neglected could potentially result in biased and unreliable outcomes. Hence, although we have worked on one example non-standard cosmological model in this thesis, this work could be viewed as a demonstration of a thought through process of testing one's model against observations which can be applied to every other preferred model