The surprisingly steep mass profile of A1689, from a lensing analysis of subaru images

T. Broadhurst, M. Takada, K. Umetsu, X. Kong, N. Arimoto, M. Chiba, Toshifumi Futamase

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206 Citations (Scopus)


Subaru observations of A1689 (z = 0.183) are used to derive an accurate, model-independent mass profile for the entire cluster, r ≲ 2 Mpc h -1 by combining magnification bias and distortion measurements. The projected mass profile steepens quickly with increasing radius, falling away to zero at r ∼ 1.0 Mpc h-1, well short of the anticipated virial radius. Our profile accurately matches the inner profile, r ≲ 200 kpc h-1, derived from deep Hubble Space Telescope Advanced Camera for Surveys (ACS) images. The combined ACS and Subaru information is well fitted by a Navarro-Frenk-White profile with virial mass, (1.93±0.20) × 1015 M⊙, and surprisingly high concentration, cvir = 13.7-1.1+1.4, significantly larger than theoretically expected (cvir≃4), corresponding to a relatively steep overall profile. A slightly better fit is achieved with a steep power-law model, d log Σ(θ)/d log θ ≃ -3, with a core θCi ≃ 1.′7 (rc≃210 kpc h-1), whereas an isothermal profile is strongly rejected. These results are based on a reliable sample of background galaxies selected to be redder than the cluster E/S0 sequence. By including the faint blue galaxy population, a much smaller distortion signal is found, demonstrating that blue cluster members significantly dilute the true signal for r ≲ 400 kpc h-1. This contamination is likely to affect most weak lensing results to date.

Original languageEnglish
Pages (from-to)L143-L146
JournalAstrophysical Journal
Issue number2 II
Publication statusPublished - 2005 Feb 1


  • Cosmology: observations
  • Galaxies: clusters: individual (A1689)
  • Gravitational lensing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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