Master thesis defense by Jaan Kasak

Gravitational waves from inflation and their manifestation through the B-mode of CMB polarisation

Since the first detection of the CMB and its anisotropies, the resolution of available data has been gradually increasing, and each upgrade provides new insight into the earliest moments of the universe. The latest full-sky CMB experiment was the powerful Planck satellite, and regular releases from the Planck collaboration provide ample research opportunities and chances to verify cosmological models. The prevailing theory for primordial times is inflation, and one theoretical prediction is the presence of primordial gravitational waves that could be detected in a B mode signal of the CMB polarisation. However, the weakness of the polarisation signal and presence of foreground contamination require massive amounts of statistical work to confirm such a signal. In this work, an implementation of one such statistical method is developed and applied to the outputs of the main component separation methods in the latest Planck 2018 release.