A Measurement of the Correlation of Galaxy Surveys with CMB Lensing Convergence Maps from the South Pole Telescope

TL;DR

This study demonstrates a significant correlation between CMB lensing maps from the South Pole Telescope and galaxy surveys, confirming theoretical predictions and showcasing the potential of this method for cosmological research.

Contribution

It provides the first robust detection of cross-correlation between SPT CMB lensing maps and multiple galaxy surveys, validating the technique and its consistency with theoretical models.

Findings

Detected >4 sigma correlation between SPT lensing maps and galaxy density maps

Measured galaxy bias consistent with previous studies

Confirmed agreement of cross-power spectra with theoretical expectations

Abstract

We compare cosmic microwave background lensing convergence maps derived from South Pole Telescope (SPT) data with galaxy survey data from the Blanco Cosmology Survey, the Wide-field Infrared Survey Explorer, and a new large Spitzer/IRAC field designed to overlap with the SPT survey. Using optical and infrared catalogs covering between 17 and 68 square degrees of sky, we detect correlation between the SPT convergence maps and each of the galaxy density maps at >4 sigma, with zero cross-correlation robustly ruled out in all cases. The amplitude and shape of the cross-power spectra are in good agreement with theoretical expectations and the measured galaxy bias is consistent with previous work. The detections reported here utilize a small fraction of the full 2500 square degree SPT survey data and serve as both a proof of principle of the technique and an illustration of the potential of this emerging cosmological probe.