DR. DHIRAJ HAZRA

The standard model of cosmology assumes the primordial perturbations to be Gaussian and to have a power law spectrum. Supporting observations also suggest that the Universe consists of baryons, radiation, cold dark matter and cosmological constant as dark energy. Cosmic Microwave Background (CMB) temperature and polarization spectra are the best probes till date, to test most of these assumptions. The speaker will discuss a model independent reconstruction of the primordial power spectrum directly using the CMB angular power spectrum data from Planck. Direct reconstruction hints towards possible features in the data, which in turn indicate non-trivial inflationary dynamics. He will demonstrate the generation of these features in the primordial power spectra involving canonical scalar field driven inflation models, particularly in the Wiggly Whipped Inflation framework. He will introduce the BI-spectra and Non-Gaussianity Operator (BINGO) for the efficient numerical computation of the primordial power spectrum and bi-spectrum. After presenting the recent constraints on the primordial features, he will discuss the extent to which we will be able to identify these features with future space based CMB surveys. Introducing poly-reion (a new free-form parametrization of the history of reionization), he will present model independent constraints on reionization from CMB and quasar data. Using this non-standard model of reionization history, he will address its degeneracies with other cosmological processes in the CMB data. Towards the end of his talk, in order to examine another assumption of the standard model, the speaker will discuss a model independent test of the isotropy of the matter dominated Universe using the Lyman-alpha forest data from the high redshift quasars.