Imprints of gravitational lensing in the Planck CMB data at the location of WISExSCOS galaxies

TL;DR

This study detects weak gravitational lensing of the CMB at galaxy locations using Planck data, estimating galaxy masses and their evolution, with implications for future surveys.

Contribution

First detection of CMB lensing at WISExSCOS galaxy locations and analysis of galaxy mass evolution across redshift slices.

Findings

Average galaxy mass M$_{200_{ m crit}}$ = 6.25 ± 0.6 × 10^{12} M$_\\odot$

Null hypothesis of no-lensing rejected at 17σ

Mass estimates increase with redshift, possibly due to selection effects.

Abstract

We detect weak gravitational lensing of the cosmic microwave background (CMB) at the location of the WISExSCOS (WxS) galaxies using the publicly available Planck lensing convergence map. By stacking the lensing convergence map at the position of 12.4 million galaxies in the redshift range $0.1\le z \le 0.345$, we find the average mass of the galaxies to be M$_{200_{\rm crit}}$ = 6.25 $\pm$ 0.6 $\times 10^{12}\ M_{\odot}$. The null hypothesis of no-lensing is rejected at a significance of $17\sigma$. We split the galaxy sample into three redshift slices each containing $\sim$4.1 million objects and obtain lensing masses in each slice of 4.18 $\pm$ 0.8, 6.93 $\pm$ 0.9, and 18.84 $\pm$ 1.2 $\times\ 10^{12}\ \mbox{M}_{\odot}$. Our results suggest a redshift evolution of the galaxy sample masses but this apparent increase might be due to the preferential selection of intrinsically luminous sources at high redshifts. The recovered mass of the stacked sample is reduced by 28% when we remove the galaxies in the vicinity of galaxy clusters with mass M$_{200_{\rm crit}}$ = $2 \times 10^{14}\ \mbox{M}_{\odot}$. We forecast that upcoming CMB surveys can achieve 5% galaxy mass constraints over sets of 12.4 million galaxies with M$_{200_{\rm crit}}$ = $1 \times 10^{12}\ M_{\odot}$ at $z=1$.