The Projected Dark and Baryonic Ellipsoidal Structure of 20 CLASH Galaxy Clusters

Keiichi Umetsu, Mauro Sereno, Sut Ieng Tam, I. Non Chiu, Zuhui Fan, Stefano Ettori, Daniel Gruen, Teppei Okumura, Elinor Medezinski, Megan Donahue, Massimo Meneghetti, Brenda Frye, Anton Koekemoer, Tom Broadhurst, Adi Zitrin, Italo Balestra, Narciso Benítez, Yuichi Higuchi, Peter Melchior, Amata MercurioJulian Merten, Alberto Molino, Mario Nonino, Marc Postman, Piero Rosati, Jack Sayers, Stella Seitz

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46 Scopus citations


We reconstruct the two-dimensional (2D) matter distributions in 20 high-mass galaxy clusters selected from the CLASH survey by using the new approach of performing a joint weak gravitational lensing analysis of 2D shear and azimuthally averaged magnification measurements. This combination allows for a complete analysis of the field, effectively breaking the mass-sheet degeneracy. In a Bayesian framework, we simultaneously constrain the mass profile and morphology of each individual cluster, assuming an elliptical Navarro-Frenk-White halo characterized by the mass, concentration, projected axis ratio, and position angle (PA) of the projected major axis. We find that spherical mass estimates of the clusters from azimuthally averaged weak-lensing measurements in previous work are in excellent agreement with our results from a full 2D analysis. Combining all 20 clusters in our sample, we detect the elliptical shape of weak-lensing halos at the 5σ significance level within a scale of 2 Mpc h-1. The median projected axis ratio is 0.67 ± 0.07 at a virial mass of Mvir = (15.2 ± 2.8) × 1014 M, which is in agreement with theoretical predictions from recent numerical simulations of the standard collisionless cold dark matter model. We also study misalignment statistics of the brightest cluster galaxy, X-ray, thermal Sunyaev-Zel'dovich effect, and strong-lensing morphologies with respect to the weak-lensing signal. Among the three baryonic tracers studied here, we find that the X-ray morphology is best aligned with the weak-lensing mass distribution, with a median misalignment angle of |ΔPA| = 21° ± 7°. We also conduct a stacked quadrupole shear analysis of the 20 clusters assuming that the X-ray major axis is aligned with that of the projected mass distribution. This yields a consistent axis ratio of 0.67 ± 0.10, suggesting again a tight alignment between the intracluster gas and dark matter.

Original languageEnglish (US)
Article number104
JournalAstrophysical Journal
Issue number2
StatePublished - Jun 20 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • cosmology: observations
  • dark matter
  • galaxies: clusters: general
  • galaxies: clusters: intracluster medium
  • gravitational lensing: weak


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