Constraining the kinetically dominated Universe.

In this project we explore alternative initial conditions for inflation and their consequences within different cosmological models for observables such as the cosmic microwave background (CMB). As a first step, we place ourselves in the standard LCDM cosmology and investigate the effects of an initially kinetically dominated universe on the primordial power spectrum (PPS) of scalar and tensor perturbations. This can then be extended to closed universes, where we can place an upper bound on the overall amount of inflation and thus expect the effects of kinetic dominance to be observable. These features in the PPS are translated through to the angular power spectrum of the CMB where we investigate their potential to match features in the data from the Planck satellite such as an overall lack of power on large scales and a dip in power at multipoles of 20 to 30. To that end we use Bayesian analysis tools such as MCMC and nested sampling to perform parameter estimates and model comparisons. The modern tools we use allow for a fully Bayesian approach for more complex models than considered previously.