The Atacama Cosmology Telescope: Detection of Sunyaev-Zel'dovich Decrement in Groups and Clusters Associated with Luminous Red Galaxies

TL;DR

This paper reports the detection of the Sunyaev-Zel'dovich effect in galaxy groups and clusters associated with luminous red galaxies using ACT data, linking the SZ signal to cluster mass estimates.

Contribution

It presents the first detection of SZ decrement in LRG-associated clusters and relates the SZ signal to cluster mass through simulations and lensing data.

Findings

Detected SZ decrement in LRG groups and clusters

Estimated halo masses around 10^14 solar masses

Accounted for radio source bias in SZ measurements

Abstract

We present a detection of the Sunyaev-Zel'dovich (SZ) decrement associated with the Luminous Red Galaxy (LRG) sample of the Sloan Digital Sky Survey. The SZ data come from 148 GHz maps of the equatorial region made by the Atacama Cosmology Telescope (ACT). The LRG sample is divided by luminosity into four bins, and estimates for the central Sunyaev-Zel'dovich temperature decrement are calculated through a stacking process. We detect and account for a bias of the SZ signal due to weak radio sources. We use numerical simulations to relate the observed decrement to Y200 and clustering properties to relate the galaxy luminosity bins to mass. We also use a relation between brightest cluster galaxy luminosity and cluster mass based on stacked gravitational lensing measurements to estimate the characteristic halo masses. The masses are found to be around 1e14 M_sun.