| Summary: | We report the first investigation of cool-core properties of galaxy clusters selected via their Sunyaev-Zel'dovich (SZ) effect. We use 13 galaxy clusters uniformly selected from 178 deg2 observed with the South Pole Telescope (SPT) and followed up by the Chandra X-ray Observatory. They form an approximately mass-limited sample (>3 × 10^(14) M_☉ h^(–1)_(70)) spanning redshifts 0.3 < z < 1.1. Using previously published X-ray-selected cluster samples, we compare two proxies of cool-core strength: surface brightness concentration (c_(SB)) and cuspiness (α). We find that c_(SB) is better constrained. We measure c_(SB) for the SPT sample and find several new z > 0.5 cool-core clusters, including two strong cool cores. This rules out the hypothesis that there are no z > 0.5 clusters that qualify as strong cool cores at the 5.4σ level. The fraction of strong cool-core clusters in the SPT sample in this redshift regime is between 7% and 56% (95% confidence). Although the SPT selection function is significantly different from the X-ray samples, the high-z c_(SB) distribution for the SPT sample is statistically consistent with that of X-ray-selected samples at both low and high redshifts. The cool-core strength is inversely correlated with the offset between the brightest cluster galaxy and the X-ray centroid, providing evidence that the dynamical state affects the cool-core strength of the cluster. Larger SZ-selected samples will be crucial in understanding the evolution of cluster cool cores over cosmic time. © 2012 American Astronomical Society. Received 2012 August 16; accepted 2012 October 30; published 2012 December 6. The South Pole Telescope program is supported by the National Science Foundation through grant ANT-0638937. The Munich group is supported by The Cluster of Excellence "Origin and Structure of the Universe," funded by the Excellence Initiative of the Federal Government of Germany, EXC project No. 153. Galaxy cluster research at the University of Chicago is partially supported by ...
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