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Title: The remarkable similarity of massive galaxy clusters from z~0 to z~1.9

Here, we present the results of a Chandra X-ray survey of the eight most massive galaxy clusters at z > 1.2 in the South Pole Telescope 2500 deg2 survey. We combine this sample with previously published Chandra observations of 49 massive X-ray-selected clusters at 0 < z < 0.1 and 90 Sunyaev–Zel'dovich–selected clusters at 0.25 < z < 1.2 to constrain the evolution of the intracluster medium (ICM) over the past ~10 Gyr. We find that the bulk of the ICM has evolved self-similarly over the full redshift range probed here, with the ICM density at $$r\gt 0.2{R}_{500}$$ scaling like $$E{(z)}^{2}$$. In the centers of clusters ($$r\lesssim 0.01{R}_{500}$$), we find significant deviations from self-similarity ($${n}_{e}\propto E{(z)}^{0.2\pm 0.5}$$), consistent with no redshift dependence. When we isolate clusters with overdense cores (i.e., cool cores), we find that the average overdensity profile has not evolved with redshift—that is, cool cores have not changed in size, density, or total mass over the past ~9–10 Gyr. We show that the evolving "cuspiness" of clusters in the X-ray, reported by several previous studies, can be understood in the context of a cool core with fixed properties embedded in a self-similarly evolving cluster. We find no measurable evolution in the X-ray morphology of massive clusters, seemingly in tension with the rapidly rising (with redshift) rate of major mergers predicted by cosmological simulations. We show that these two results can be brought into agreement if we assume that the relaxation time after a merger is proportional to the crossing time, since the latter is proportional to $$H{(z)}^{-1}$$.
ORCiD logo [1] ;  [2] ; ORCiD logo [1] ;  [3] ;  [4] ; ORCiD logo [5] ;  [1] ;  [4] ; ORCiD logo [6] ; ORCiD logo [7] ; ORCiD logo [8] ; ORCiD logo [9] ;  [10] ;  [2] ;  [6]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  3. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Univ. of Chicago, Chicago, IL (United States)
  4. Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
  5. Univ. of Missouri, Columbia, MO (United States)
  6. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  7. Univ. de Montreal, Montreal, QC (Canada)
  8. Huntingdon Institute for X-ray Astronomy, Huntingdon, PA (United States)
  9. Princeton Univ., Princeton, NJ (United States)
  10. Univ. of Chicago, Chicago, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; AC02-06CH11357
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 843; Journal Issue: 1; Journal ID: ISSN 1538-4357
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
National Science Foundation (NSF); National Aeronautic and Space Administration (NASA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Gordon and Betty Moore Foundation
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; galaxies: clusters: general; galaxies: clusters: intracluster medium; galaxies: high-redshift; X-rays: galaxies: clusters
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1373896