New Developments in Cosmology

TL;DR

This thesis analyzes recent cosmological data from Planck and other probes, exploring extensions of the $ ext{Lambda}$CDM model including sterile neutrinos, axions, primordial non-Gaussianities, and dark sector interactions.

Contribution

It investigates the degeneracies between new particles, primordial non-Gaussianities, and cosmological parameters, providing insights into extended cosmological models.

Findings

Degeneracy between sterile neutrinos and primordial perturbations.

Primordial non-Gaussianities can mimic power spectrum effects.

Interaction models between dark energy and dark matter explored.

Abstract

In this Thesis I discuss several recent results obtained using the CMB spectra measured by Planck and several other cosmological probes. Extensions of the $\Lambda$CDM model are studied, including the presence of an additional sterile neutrino (motivated by the short-baseline oscillation anomalies) and of a thermal axion. The degeneracies of the cosmological effects of these particles with the power spectrum of primordial perturbations are tested. We also show that the power spectrum of initial scalar perturbations can be degenerate with the presence of primordial non-Gaussianities, thus affecting the constraints on the non-Gaussianity parameter $f_{NL}$. Finally, an effective interaction between dark energy and dark matter is studied.