Detection of Gravitational Lensing in the Cosmic Microwave Background

TL;DR

This paper reports the first significant detection of gravitational lensing in the cosmic microwave background using WMAP data, enhancing our understanding of cosmological structures.

Contribution

It introduces a quadratic estimator technique applied to all-sky WMAP maps and correlates with NVSS radio galaxy counts to detect CMB lensing.

Findings

3.4 sigma detection of CMB lensing

Methodology includes detailed contaminant analysis

Error estimates account for multiple systematic uncertainties

Abstract

Gravitational lensing of the cosmic microwave background (CMB), a long-standing prediction of the standard cosmolgical model, is ultimately expected to be an important source of cosmological information, but first detection has not been achieved to date. We report a 3.4 sigma detection, by applying quadratic estimator techniques to all sky maps from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite, and correlating the result with radio galaxy counts from the NRAO VLA Sky Survey (NVSS). We present our methodology including a detailed discussion of potential contaminants. Our error estimates include systematic uncertainties from density gradients in NVSS, beam effects in WMAP, Galactic microwave foregrounds, resolved and unresolved CMB point sources, and the thermal Sunyaev-Zeldovich effect.