CMB lensing reconstruction from the WMAP 7-year data

TL;DR

This study attempts to detect weak lensing signals in WMAP 7-year data using a real-space quadratic estimator, but finds no statistically significant detection, highlighting the need for more sensitive future experiments like Planck.

Contribution

First application of a real-space quadratic estimator to WMAP data for weak lensing reconstruction, providing a framework for future higher-sensitivity measurements.

Findings

Weak lensing amplitude parameter $A_{L}=0.99\pm1.67$ obtained.

Detection not statistically significant with current data.

Method shows insensitivity to uncorrelated noise.

Abstract

We attempt to make a direct measurement of the weak lensing signal from the WMAP 7-year data. We apply the real-space implementation of the optimal quadratic estimator on the maps produced by the W-band Differencing Assemblies. We obtain a weak lensing amplitude parameter of $A_{L}=0.99\pm1.67$ after correcting for several sources of bias. The error budget includes a contribution from the bias removal procedure. Despite the demonstrated insensitivity of the real-space estimator to uncorrelated noise, we conclude that this detection is not statistically significant. We expect that a full-sky, higher-sensitivity experiment such as Planck will allow us to make a more significant measurement.