Astrophys. J., 642, 720-733 (2006/May-2)
Weak-lensing Detection at z ∼ 1.3: Measurement of the two Lynx clusters with the Advanced Camera for Surveys.
JEE M.J., WHITE R.L., FORD H.C., ILLINGWORTH G.D., BLAKESLEE J.P., HOLDEN B. and MEI S.
Abstract (from CDS):
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 z850imaging, 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)x1014 and (2.1±0.7)x1014 M☉, 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 TX=3.8+1.3–0.7 and 1.7+0.7–0.4keV 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 2.3+0.8–0.4x1014 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 (6.3+2.6–1.5x1013 M☉) than the weak-lensing measurement.
Cosmology: Observations - Cosmology: Dark Matter - galaxies: clusters: individual (RX J0849+4452) - galaxies: clusters: individual (RX J0848+4453) - Galaxies: High-Redshift - Cosmology: Gravitational Lensing - X-Rays: Galaxies: Clusters
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