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This content will become publicly available on February 4, 2017

Title: Cosmology and astrophysics from relaxed galaxy clusters - IV: Robustly calibrating hydrostatic masses with weak lensing

This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses measures the combined bias of X-ray hydrostatic masses from both astrophysical and instrumental sources. While we cannot disentangle the two sources of bias, only the combined bias is relevant for calibrating cosmological measurements using relaxed clusters. Assuming a fixed cosmology, and within a characteristic radius (r2500) determined from the X-ray data, we measure a lensing to X-ray mass ratio of 0.96 ± 9% (stat) ± 9% (sys). We find no significant trends of this ratio with mass, redshift or the morphological indicators used to select the sample. Our results imply that any departures from hydrostatic equilibrium at these radii are offset by calibration errors of comparable magnitude, with large departures of tens-of-percent unlikely. In addition, we find a mean concentration of the sample measured from lensing data of c200 = 3.0+4.4–1.8. In conclusion, anticipated short-term improvements in lensing systematics, and a modest expansionmore » of the relaxed lensing sample, can easily increase the measurement precision by 30–50%, leading to similar improvements in cosmological constraints that employ X-ray hydrostatic mass estimates, such as on Ωm from the cluster gas mass fraction.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10]
  1. Argelander-Institut fur Astronomie, Bonn (Germany)
  2. Univ. of Chicago, Chicago, IL (United States); Stanford Univ., Stanford, CA (United States)
  3. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. Stanford Univ., Stanford, CA (United States); Niels Bohr Institute, Univ. of Copenhagen Julian Maries Vej, Copenhagen (Denmark)
  5. Exzellenzcluster Universe, Garching (Germany); Ludwig-Maximilians-Univ., Univ.-Sternwarte, Munchen (Germany)
  6. Univ. of California, Berkeley, CA (United States)
  7. Stanford Univ., Stanford, CA (United States)
  8. Institute of Astronomy, Honolulu, HI (United States)
  9. Niels Bohr Institute, Univ. of Copenhagen Julian Maries Vej, Copenhagen (Denmark)
  10. Astronomisches Rechen-Institut, Zentrum fur Astronomie der Univ. Heidelberg, Heidelberg (Germany)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0035-8711
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 457; Journal Issue: 2; Journal ID: ISSN 0035-8711
Royal Astronomical Society
Research Org:
SLAC National Accelerator Laboratory (SLAC)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS gravitational lensing: weak; galaxies: clusters: general; cosmology: observations; X-rays: galaxies: clusters