Testing for X-Ray-SZ Differences and Redshift Evolution in the X-Ray Morphology of Galaxy Clusters

• Main Authors: Nurgaliev, D. (Author), Benson, B. A. (Author), Bleem, L. (Author), Bocquet, S. (Author), Forman, W. R. (Author), Garmire, G. P. (Author), Gupta, N. (Author), Hlavacek-Larrondo, J. (Author), Mohr, J. J. (Author), Nagai, D. (Author), Rapetti, D. (Author), Stark, A. A. (Author), Stubbs, C. W. (Author), Vikhlinin, A. (Author), McDonald, Michael A. (Contributor)
• Other Authors: MIT Kavli Institute for Astrophysics and Space Research (Contributor)
• Format: Article
• Language: English
• Published: IOP Publishing, 2017-11-01T15:48:43Z.
• Subjects: Article
• Online Access: Get fulltext

 We present a quantitative study of the X-ray morphology of galaxy clusters, as a function of their detection method and redshift. We analyze two separate samples of galaxy clusters: a sample of 36 clusters at 0.35 < z < 0.9 selected in the X-ray with the ROSAT PSPC 400 deg 2 survey, and a sample of 90 clusters at 0.25 < z < 1.2 selected via the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope. Clusters from both samples have similar-quality Chandra observations, which allow us to quantify their X-ray morphologies via two distinct methods: centroid shifts (w) and photon asymmetry (A phot ). The latter technique provides nearly unbiased morphology estimates for clusters spanning a broad range of redshift and data quality. We further compare the X-ray morphologies of X-ray- and SZ-selected clusters with those of simulated clusters. We do not find a statistically significant difference in the measured X-ray morphology of X-ray and SZ-selected clusters over the redshift range probed by these samples, suggesting that the two are probing similar populations of clusters. We find that the X-ray morphologies of simulated clusters are statistically indistinguishable from those of X-ray- or SZ-selected clusters, implying that the most important physics for dictating the large-scale gas morphology (outside of the core) is well-approximated in these simulations. Finally, we find no statistically significant redshift evolution in the X-ray morphology (both for observed and simulated clusters), over the range of z ∼ 0.3 to z ∼ 1, seemingly in contradiction with the redshift-dependent halo merger rate predicted by simulations.