Weak-lensing Results for the Merging Cluster A1758

Abstract

Here we present the weak-lensing results for A1758, which is known to consist of four subclusters undergoing two separate mergers, A1758N and A1758S. Weak-lensing results for A1758N agree with previous weak-lensing results for clusters 1E0657-558 (Bullet cluster) and MACS J0025.4-1222, whose X-ray gas components were found to be largely separated from their clusters' gravitational potentials. A1758N has a geometry that is different from previously published mergers in that one of its X-ray peaks overlays the corresponding gravitational potential and the other X-ray peak is well separated from its cluster's gravitational potential. The weak-lensing mass peaks of the two northern clusters are separated at the 2.5σ level. We estimate the combined mass of the clusters in A1758N to be (2.2 ± 0.5) × 10¹⁵ M _⊙ and r ₂₀₀ = 2300⁺¹⁰⁰ _{- 130} kpc. We also detect seven strong-lensing candidates, two of which may provide information that would improve the mass measurements of A1758N.

Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555, under program 11194. Also based on data collected at the Subaru Telescope and partly obtained from SMOKA, which is operated by the National Astronomical Observatory of Japan.