A Demonstration of Spectral Level Reconstruction of Intrinsic $B$-mode Power

TL;DR

This paper presents a spectral reconstruction method for primordial B-mode power that can estimate the tensor-to-scalar ratio with minimal noise impact, potentially up to multipoles of 500, aiding future CMB experiments.

Contribution

It introduces a spectral level reconstruction technique for primordial B-mode power that can bypass instrumental noise and provide cosmic variance limited estimates up to high multipoles.

Findings

Reconstruction can estimate tensor-to-scalar ratio accurately.

Instrumental noise effects can be mitigated in the method.

Potential for application in future space missions like COrE.

Abstract

We investigate the prospects and consequences of the spectral level reconstruction of primordial $B$-mode power by solving the systems of linear equations assuming that the lensing potential together with the lensed polarization spectra are already in hand. We find that this reconstruction technique may be very useful to have an estimate of the amplitude of primordial gravity waves or more specifically the value of tensor to scalar ratio. We also see that one can have cosmic variance limited reconstruction of the intrinsic $B$-mode power up to few hundred multipoles ($\ell\sim500$) which is more than sufficient to have an estimate of the tensor to scalar ratio. Since the small scale cosmic microwave background (CMB henceforth) anisotropies are not sourced by the primordial gravity waves generated during inflation. We also find that the impact of instrumental noise may be bypassed within this reconstruction algorithm. A simple demonstration for the nullification of the instrumental noise anticipating COrE like futuristic space mission complemented with Planck 2013 cosmology has been presented.