Demonstration of cosmic microwave background delensing using the cosmic infrared background

TL;DR

This paper demonstrates the first successful delensing of Planck CMB temperature maps using the cosmic infrared background, significantly sharpening acoustic peaks and paving the way for improved primordial B-mode polarization measurements.

Contribution

It presents the first practical application of CIB-based delensing on Planck data, reducing lensing effects and confirming theoretical expectations.

Findings

Lensing effects in the temperature power spectrum are reduced as expected.

The acoustic peaks are sharpened with a significance of 16σ.

The delensing amplitude is measured as 1.12 ± 0.07.

Abstract

Delensing is an increasingly important technique to reverse the gravitational lensing of the cosmic microwave background (CMB) and thus reveal primordial signals the lensing may obscure. We present a first demonstration of delensing on Planck temperature maps using the cosmic infrared background (CIB). Reversing the lensing deflections in Planck CMB temperature maps using a linear combination of the 545 and 857GHz maps as a lensing tracer, we find that the lensing effects in the temperature power spectrum are reduced in a manner consistent with theoretical expectations. In particular, the characteristic sharpening of the acoustic peaks of the temperature power spectrum resulting from successful delensing is detected at a significance of 16$\rm{\sigma}$, with an amplitude of $A_{\rm{delens}} = 1.12 \pm 0.07$ relative to the expected value of unity. This first demonstration on data of CIB delensing, and of delensing techniques in general, is significant because lensing removal will soon be essential for achieving high-precision constraints on inflationary B-mode polarization.