Detection of dark matter concentrations in the field of CL 1604+4304 from weak lensing analysis

Keiichi Umetsu, Toshifumi Futamase

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


We present a weak lensing analysis of a region around the galaxy cluster Cl 1604+4304 (z = 0.897) on the basis of the deep observations with the Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 (WFPC2). We apply a variant of Schneider's aperture mass technique to the observed WFPC2 field and obtain the distribution of weak lensing signal-to-noise ratio (S/N) within the field. The resulting S/N map reveals a clear pronounced peak located about 1′.7 (850 h-150 kpc at z = 0.897) southwest of the second peak associated with the optical cluster center determined from the dynamical analysis of Postman et al. A nonlinear finite-field inversion method has been used to reconstruct the projected mass distribution from the observed shear field. The reconstructed mass map shows a supercritical feature at the location of the S/N peak as well as in the cluster central region. Assuming the redshift distribution of field galaxies, we obtain the total mass in the observed field to be 1.0 × 1015 h-150 M for 〈z〉 = 1.0. The estimated mass within a circular aperture of radius 280 h-150 kpc centered on the dark clump is 2.4 × 1014 h-150 M. We have confirmed the existence of the "dark" mass concentration from another deep HST observation with a slightly different (∼20″) pointing.

Original languageEnglish
Pages (from-to)L5-L8
JournalAstrophysical Journal
Issue number1 PART 2
Publication statusPublished - 2000 Aug 10


  • Cosmology: observations
  • Dark matter
  • Gravitational lensing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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