A demonstration of spectral level reconstruction of intrinsic B-mode power

We investigate the prospects and consequences of the spectral level reconstruction of primordial B-mode power by solving the system of linear equation. We find that this reconstruction technique may be very useful to estimate the amplitude of primordial gravity waves or more specifically, the value of tensor-to-scalar ratio. We also see that one may have very accurate reconstruction of the intrinsic B-mode power up to a few hundred multipoles which is more than sufficient to estimate the tensor-to-scalar ratio. The small-scale cosmic microwave background (CMB) anisotropies are not sourced by the primordial gravity waves generated during inflation. We have also demonstrated the efficiency of our algorithm by incorporating the impact of instrumental noise considering CMB-Bharat-like futuristic space mission complemented with Planck 2018 cosmology. We shall see that spectral delensing is capable of reducing the variance in lensed CMB. We do not make any conclusive comments on this as the true non-Gaussian structure and errors in the observed CMB along with the lensing by gravity waves have been ignored.