Reconstruction of Gravitational Lensing Using WMAP 7-Year Data

TL;DR

This paper attempts to reconstruct gravitational lensing from WMAP 7-year data using a four-point estimator, but finds the data insufficient for a definitive detection of lensing signals.

Contribution

It demonstrates the application of a four-point estimator to WMAP data for lensing reconstruction and assesses the limitations of WMAP data in detecting lensing.

Findings

Measured a lensing signal with amplitude 1.27±0.98

WMAP 7-year data alone cannot detect gravitational lensing

Biases were simulated and subtracted in the analysis

Abstract

Gravitational lensing by large scale structure introduces non-Gaussianity into the Cosmic Microwave Background and imprints a new observable, which can be used as a cosmological probe. We apply a four-point estimator to the Wilkinson Microwave Anisotropy Probe (WMAP) 7-year coadded temperature maps alone to reconstruct the gravitational lensing signal. The Gaussian bias is simulated and subtracted, and the higher order bias is investigated. We measure a gravitational lensing signal with a statistical amplitude of $\mathcal {C}$ = $1.27\pm 0.98$ using all the correlations of the W- and V-band Differencing Assemblies (DAs). We therefore conclude that WMAP 7-year data alone, can not detect lensing.