Correlation of CMB with large-scale structure: II. Weak lensing

TL;DR

This study examines the correlation between CMB lensing and large-scale structure tracers, finding a positive signal consistent with cosmological expectations and carefully accounting for potential contaminants.

Contribution

It presents a detailed analysis of CMB lensing correlation with multiple large-scale structure tracers, including bias and redshift distribution considerations, extending previous work.

Findings

Positive cross-correlation detected at 2.5σ significance

Correlation amplitude consistent with WMAP cosmological parameters

Contaminant effects found to be negligible

Abstract

We investigate the correlation of gravitational lensing of the cosmic microwave background (CMB) with several tracers of large-scale structure, including luminous red galaxies (LRGs), quasars, and radio sources. The lensing field is reconstructed based on the CMB maps from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite; the LRGs and quasars are observed by the Sloan Digital Sky Survey (SDSS); and the radio sources are observed in the NRAO VLA Sky Survey (NVSS). Combining all three large-scale structure samples, we find evidence for a positive cross-correlation at the $2.5\sigma$ level ($1.8\sigma$ for the SDSS samples and $2.1\sigma$ for NVSS); the cross-correlation amplitude is $1.06\pm 0.42$ times that expected for the WMAP cosmological parameters. Our analysis extends other recent analyses in that we carefully determine bias weighted redshift distribution of the sources, which is needed for a meaningful cosmological interpretation of the detected signal. We investigate contamination of the signal by Galactic emission, extragalactic radio and infrared sources, thermal and kinetic Sunyaev-Zel'dovich effects, and the Rees-Sciama effect, and find all of them to be negligible.