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 .