Hydrostatic and Caustic Mass Profiles of Galaxy Clusters

Ben J. Maughan, Paul A. Giles, Kenneth J. Rines, Antonaldo Diaferio, Margaret J. Geller, Nina Van Der Pyl, Massimiliano Bonamente

Research output: Contribution to journalArticle (Academic Journal)peer-review

28 Citations (Scopus)
302 Downloads (Pure)


We compare X-ray and caustic mass profiles for a sample of 16 massive galaxy clusters. We assume hydrostatic equilibrium in interpreting the X-ray data, and use large samples of cluster members with redshifts as a basis for applying the caustic technique. The hydrostatic and caustic masses agree to better than ≈20% on average across the radial range covered by both techniques (~[0.2-1.25]R500). The mass profiles were measured independently and do not assume a common functional form. Previous studies suggest that, at R500, the hydrostatic and caustic masses are biased low and high respectively. We find that the ratio of hydrostatic to caustic mass at R500 is 1.20 +0.13 -0.11; thus it is larger than 0.9 at ≈3σ and the combination of under- and over-estimation of the mass by these two techniques is ≈10% at most. There is no indication of any dependence of the mass ratio on the X-ray morphology of the clusters, indicating that the hydrostatic masses are not strongly systematically affected by the dynamical state of the clusters. Overall, our results favour a small value of the so-called hydrostatic bias due to non-thermal pressure sources.
Original languageEnglish
Pages (from-to)4182-4191
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date7 Jul 2016
Publication statusPublished - 1 Oct 2016

Bibliographical note

10 pages (including appendix), 6 figures. MNRAS in press


  • astro-ph.CO
  • galaxies: clusters: general
  • galaxies: kinematics and dynamics
  • cosmology: observations
  • X-rays: galaxies: clusters


Dive into the research topics of 'Hydrostatic and Caustic Mass Profiles of Galaxy Clusters'. Together they form a unique fingerprint.

Cite this