Measuring cluster masses with Planck and SPT-SZ CMB lensing

Abstract

Galaxy cluster masses help to constrain cosmological parameters through the halo mass function. To get rid of major biases in the mass measurement, we directly probe the cluster gravitational potentials by observing their gravitational lensing on the Cosmic Microwave Background (CMB). We measured the average mass of a 468-cluster sample using SPT-SZ and Planck/HFI PR2 sky maps and compared it with the masses provided in the SPT-SZ data set. We found an average mass ratio of $M_{\rm CMBlens}/M_{\rm SZ} = 0.98 \pm 0.19$ (stat.) $\pm 0.03$ (syst.) [arxiv:2402.18346], in agreement with SPT-SZ masses. We also showed that the CMB large scales are important for the reconstruction of the lensing potential of a cluster with a quadratic estimator.