Galaxy Clusters Selected via the Sunyaev-Zel'dovich Effect in 5 year data from the SPT-3G Main Survey

Abstract

We report a new galaxy cluster catalog, selected using the thermal Sunyaev-Zel'dovich (SZ) effect, from 5 years of observations of the SPT-3G Main field. Drawn from arcminute-resolution data with white noise levels of 3.2, 2.5, and 8.9 $\hat{I}¼$K-arcmin at 95, 150, and 220 GHz, respectively, the sample consists of 8,892 cluster candidates detected above significance $\hat{I}¾=4$, with an expected purity of $>82\%$ (4,480 at $\hat{I}¾\ge 5$ with purity $>99\%$). Using optical and infrared data we have confirmed 7,190 candidates as clusters. The sample spans a mass range $7.9\times 10^{13}$ $M_{\odot }/h_{70}$ \ $<M_{\text{500c}}<$ $1.6\times 10^{15}$ $M_{\odot }/h_{70}$ with a median mass of $1.65\times 10^{14}$ $M_{\odot }/h_{70}$, and a redshift range of $0.037<z\lesssim 2$ with a median redshift of $z_{\text{med}}$ = 0.73; 1,780 clusters are at $z>1$ and 271 at $z>1.5$. Compared to previous SZ cluster samples from South Pole Telescope and Atacama Cosmology Telescope data, the SPT-3G sample is highly consistent in mass and redshift but is significantly deeper, with per-cluster detection signal-to-noise 2-4 times higher and a cluster density of 4.5 confirmed clusters/deg${}^2$. We cross match with eRASS1 cluster and point source catalogs, finding 1,279 and 1,319 matches, respectively. The SPT and eROSITA cluster mass estimates are in relatively good agreement. We perform a series of validation checks using both internal data splits and comparisons to external samples. These tests show increasing correlated (dusty) emission with redshift, with a $\sim 17\times$ larger 220 GHz temperature increment for clusters at $z\sim 1.5$ than $z\sim 0.25$, but only weak evidence for correlated synchrotron emission. Finally, a number of clusters are flagged as candidate strong gravitational lenses.

Cluster sample online available at https://pole.uchicago.edu/public/data/spt3g-clusters/