Quest for primordial B-modes in CMB: Foreground issues

Detection of the primordial B-mode polarization in CMB is considered as one of the ultimate challenges of cosmology in the coming decades. B-modes contain an unequivocal signal of the gravitational waves generated during the epoch of inflation. There are several upcoming facilities that will be searching for B-modes from the ground, e.g., CMB-S4, Simons Observatory etc., and from space, e.g., LiteBIRD, PICO, CMB-Bharat etc. with unprecedented sensitivity. However, to claim the detection, the major challenge we have to face is removing the polarized dust and synchrotron emission from our Galaxy that obscure B-modes by order of magnitudes. Therefore, the foreground issue is a major focus of research for the quest for B-modes, which I will demonstrate over the course of this talk. I will discuss the modelling and estimating spectral properties of CMB foregrounds. I will also focus on developing a component separation algorithm to subtract foregrounds from CMB and the impact of the residual leakage of foregrounds on the detection of B-modes for future high sensitive instruments.