Cosmic microwave background

The cosmic microwave background (CMB) is thermal radiation coming from an early stage of the Universe evolution. The small deviations in intensity and polarisation of the CMB from point to point on the sky carry unique information about the Universe at the moment of decoupling of radiation from baryonic matter around 380 000 years after the Big Bang. Driven by the mechanism of gravitational instability these tiny fluctuations in matter distribution formed the observed large-scale structure and galaxies. In the properties of CMB there are also encoded informations about interactions of CMB photons, travelling from the last scattering surface, with the large-scale structure. It gives us an opportunity to study the evolution of the structure.

In our department we are studying statistical properties of CMB maps, such as statistical isotropy and Gaussianity, as well as CMB anisotropy coming from interplay of CMB with the large-scale structure of the Universe. In particular, we study the CMB gravitational lensing effect which enables to trace distribution and evolution of dark matter and test validity of General Relativity. The effect is also a source of serious contamination for a search for the signatures of the primordial gravitational waves in CMB maps. For this reason there is a need of better understanding and reducing the lensing component from the maps. In these studies we use the state-of-the art data from the Planck experiment and galaxy catalogues from projects such as the Dark Energy Survey and Herschel Extragalactic Legacy Project. We are also involved in preparations for the analysis of data from forthcoming CMB experiments and galaxy surveys.