Weak-lensing detection at z ∼ 1.3: Measurement of the two Lynx clusters with the advanced camera for surveys

M. J. Jee, R. L. White, H. C. Ford, G. D. Illingworth, J. P. Blakeslee, B. Holden, S. Mei

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32 Citations (Scopus)


We present a Hubble Space Telescope Advanced Camera for Surveys (ACS) weak-lensing study of RX J0849+4452 and RX J0848+4453, the two most distant (at z = 1.26 and 1.27, respectively) clusters yet measured with weak lensing. The two clusters are separated by ∼4′ from each other and appear to form a supercluster in the Lynx field. Using our deep ACS i775 and z 850 imaging, we detected weak-lensing signals around both clusters at ∼4 σ levels. The mass distribution indicated by the reconstruction map is in good spatial agreement with the cluster galaxies. From the singular isothermal sphere (SIS) fitting, we determined that RX J0849+4452 and RX J0848+4453 have similar projected masses of (2.0 ± 0.6) × 10 14 and (2.1 ± 0.7) × 1014 Modot;, respectively, within a 0.5 Mpc (∼60″) aperture radius. In order to compare the weak-lensing measurements with the X-ray results calibrated by the most recent low-energy quantum efficiency determination and time-dependent gain correction, we also reanalyzed the archival Chandra data and obtained T X = 3.8-0.7+1.3 and 1.70.4 0.7 keV for RX J0849+4452 and RX J0848+4453, respectively. Combined with the X-ray surface brightness profile measurement under the assumption of an isothermal β-model, the temperature of RX J0849+ 4452 predicts that the projected mass of the cluster within r = 0.5 Mpc is 2.30.4 +0.4 × 1014 M, consistent with the weak-lensing analysis. On the other hand, for RX J0848+4453 we find that the mass derived from this X-ray analysis is much smaller (6.31.5 2.6 × 1013 Modot;) than the weak-lensing measurement.

Original languageEnglish
Pages (from-to)720-733
Number of pages14
JournalAstrophysical Journal
Issue number2 I
Publication statusPublished - 2006 May 10

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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