Theory seminar. Probing the early universe through the Cosmic Microwave Background

Parampreet Singh Walia, UiO

The cosmological predictions of the angular power spectrum and structure formation are dependent on the chosen initial conditions of perturbations at early radiation dominated epoch.  I will start by introducing the general mathematically possible initial conditions for scalar perturbations. Single field inflationary models produce Adiabatic initial conditions and the current CMB data strongly supports adiabatic initial conditions. With multi-field inflationary models one can produce isocurvature perturbations. A signal for isocurvature perturbations is of high importance for particle physicists as they predict the existence of exotic particles like axions and curvatons. I would  present my work on trying to find an evidence for a (possibly) correlated adiabatic and isocurvature mode. The CMB datasets used for constraining models are WMAP9, QUaD and ACBAR. In the end, I would discuss the current status of isocurvature perturbations after PLANCK.