The SPTpol Extended Cluster Survey
Authors: Bleem L. E. , Bocquet S. , Stalder B. , Gladders M. D. , Ade P. A. R. , Allen S. W. , Anderson A. J. , Annis J. , Ashby M. L. N. , Austermann J. E. , Avila S. , Avva J. S. , Bayliss M. , Beall J. A. , Bechtol K. , Bender A. N. , Benson B. A. , Bertin E. , Bianchini F. , Blake C. , Brodwin M. , Brooks D. , Buckley-Geer E. , Burke D. L. , Carlstrom J. E. , Rosell A. Carnero , Carrasco Kind M. , Carretero J. , Chang C. L. , Chiang H. C. , Citron R. , Moran C. Corbett , Costanzi M. , Crawford T. M. , Crites A. T. , da Costa L. N. , de Haan T. , De Vicente J. , Desai S. , Diehl H. T. , Dietrich J. P. , Dobbs M. A. , Eifler T. F. , Everett W. , Flaugher B. , Floyd B. , Frieman J. , Gallicchio J. , García-Bellido J. , George E. M. , Gerdes D. W. , Gilbert A. , Gruen D. , Gruendl R. A. , Gschwend J. , Gupta N. , Gutierrez G. , Halverson N. W. , Harrington N. , Henning J. W. , Heymans C. , Holder G. P. , Hollowood D. L. , Holzapfel W. L. , Honscheid K. , Hrubes J. D. , Huang N. , Hubmayr J. , Irwin K. D. , James D. J. , Jeltema T. , Joudaki S. , Khullar G. , Klein M. , Knox L. , Kuropatkin N. , Lee A. T. , Li D. , Lidman C. , Lowitz A. , MacCrann N. , Mahler G. , Maia M. A. G. , Marshall J. L. , McDonald M. , McMahon J. J. , Melchior P. , Menanteau F. , Meyer S. S. , Miquel R. , Mocanu L. M. , Mohr J. J. , Montgomery J. , Nadolski A. , Natoli T. , Nibarger J. P. , Noble G. , Novosad V. , Padin S. , Palmese A. , Parkinson D. , Patil S. , Paz-Chinchón F. , Plazas A. A. , Pryke C. , Ramachandra N. S. , Reichardt C. L. , Remolina González J. D. , Romer A. K. , Roodman A. , Ruhl J. E. , Rykoff E. S. , Saliwanchik B. R. , Sanchez E. , Saro A. , Sayre J. T. , Schaffer K. K. , Schrabback T. , Serrano S. , Sharon K. , Sievers C. , Smecher G. , Smith M. , Soares-Santos M. , Stark A. A. , Story K. T. , Suchyta E. , Tarle G. , Tucker C. , Vanderlinde K. , Veach T. , Vieira J. D. , Wang G. , Weller J. , Whitehorn N. , Wu W. L. K. , Yefremenko V. , Zhang Y. 
Published: March 2020

Abstract
We describe the observations and resultant galaxy cluster catalog from the 2770 deg2 SPTpol Extended Cluster Survey (SPT-ECS). Clusters are identified via the Sunyaev–Zel’dovich (SZ) effect and confirmed with a combination of archival and targeted follow-up data, making particular use of data from the Dark Energy Survey (DES). With incomplete follow-up we have confirmed as clusters 244 of 266 candidates at a detection significance ξ ≥ 5 and an additional 204 systems at 4 < ξ < 5. The confirmed sample has a median mass of

and a median redshift of z = 0.49, and we have identified 44 strong gravitational lenses in the sample thus far. Radio data are used to characterize contamination to the SZ signal; the median contamination for confirmed clusters is predicted to be ∼1% of the SZ signal at the ξ > 4 threshold, and <4% of clusters have a predicted contamination >10% of their measured SZ flux. We associate SZ-selected clusters, from both SPT-ECS and the SPT-SZ survey, with clusters from the DES redMaPPer sample, and we find an offset distribution between the SZ center and central galaxy in general agreement with previous work, though with a larger fraction of clusters with significant offsets. Adopting a fixed Planck-like cosmology, we measure the optical richness–SZ mass (

) relation and find it to be 28% shallower than that from a weak-lensing analysis of the DES data—a difference significant at the 4σ level—with the relations intersecting at λ = 60. The SPT-ECS cluster sample will be particularly useful for studying the evolution of massive clusters and, in combination with DES lensing observations and the SPT-SZ cluster sample, will be an important component of future cosmological analyses.