The Atacama Cosmology Telescope: A Catalog of > 4000 Sunyaev-Zel'dovich Galaxy Clusters

TL;DR

This paper presents a catalog of over 4000 Sunyaev-Zel'dovich galaxy clusters detected by the Atacama Cosmology Telescope, providing a valuable resource for cosmology and galaxy evolution studies.

Contribution

The first large, optically confirmed SZ-selected galaxy cluster catalog from ACT, including 868 new discoveries and spanning a wide redshift range.

Findings

Catalog contains 4195 clusters with S/N > 4 over 13,211 deg².

Includes 222 clusters at z > 1, with 868 new detections.

Provides a basis for future cosmological and astrophysical analyses.

Abstract

We present a catalog of 4195 optically confirmed Sunyaev-Zel'dovich (SZ) selected galaxy clusters detected with signal-to-noise > 4 in 13,211 deg$^2$ of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multi-frequency matched filter to 98 and 150 GHz maps constructed from ACT observations obtained from 2008-2018, and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 < z < 1.91 (median z = 0.52). The catalog contains 222 z > 1 clusters, and a total of 868 systems are new discoveries. Assuming an SZ-signal vs. mass scaling relation calibrated from X-ray observations, the sample has a 90% completeness mass limit of M500c > 3.8 x 10$^{14}$ MSun, evaluated at z = 0.5, for clusters detected at signal-to-noise ratio > 5 in maps filtered at an angular scale of 2.4'. The survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the SZ-signal mass-scaling relation, such as the Dark Energy Survey (4566 deg$^2$), the Hyper Suprime-Cam Subaru Strategic Program (469 deg$^2$), and the Kilo Degree Survey (825 deg$^2$). We highlight some noteworthy objects in the sample, including potentially projected systems; clusters with strong lensing features; clusters with active central galaxies or star formation; and systems of multiple clusters that may be physically associated. The cluster catalog will be a useful resource for future cosmological analyses, and studying the evolution of the intracluster medium and galaxies in massive clusters over the past 10 Gyr.