The Atacama Cosmology Telescope: The LABOCA/ACT Survey of Clusters at All Redshifts

TL;DR

This paper presents a multi-wavelength analysis of eleven galaxy clusters selected via the Sunyaev Zel'dovich effect from the ACT survey, combining new and existing data to study their properties, contamination sources, and peculiar velocities.

Contribution

It provides the first spatially-resolved 345GHz SZE measurements for several clusters and assesses contamination from radio sources and SMGs, improving cluster velocity constraints.

Findings

Spatially-resolved 345GHz SZE increments detected in six clusters.

Radio sources and SMGs contaminate SZE signals by up to 18%.

Average peculiar velocity of clusters is 153 km/s with large uncertainty.

Abstract

We present a multi-wavelength analysis of eleven Sunyaev Zel'dovich effect (SZE)-selected galaxy clusters (ten with new data) from the Atacama Cosmology Telescope (ACT) southern survey. We have obtained new imaging from the Large APEX Bolometer Camera (345GHz; LABOCA) on the Atacama Pathfinder EXperiment (APEX) telescope, the Australia Telescope Compact Array (2.1GHz; ATCA), and the Spectral and Photometric Imaging Receiver (250, 350, and $500\,\rm\mu m$; SPIRE) on the Herschel Space Observatory. Spatially-resolved 345GHz SZE increments with integrated S/N > 5 are found in six clusters. We compute 2.1GHz number counts as a function of cluster-centric radius and find significant enhancements in the counts of bright sources at projected radii $\theta < \theta_{2500}$. By extrapolating in frequency, we predict that the combined signals from 2.1GHz-selected radio sources and 345GHz-selected SMGs contaminate the 148GHz SZE decrement signal by ~5% and the 345GHz SZE increment by ~18%. After removing radio source and SMG emission from the SZE signals, we use ACT, LABOCA, and (in some cases) new Herschel SPIRE imaging to place constraints on the clusters' peculiar velocities. The sample's average peculiar velocity relative to the cosmic microwave background is $153\pm 383\,\rm km\,s^{-1}$.