Volume 610, February 2018
|Number of page(s)||17|
|Section||Cosmology (including clusters of galaxies)|
|Published online||08 March 2018|
Precise weak lensing constraints from deep high-resolution Ks images: VLT/HAWK-I analysis of the super-massive galaxy cluster RCS2 J 232727.7−020437 at z = 0.70★
Argelander-Institut für Astronomie, Universität Bonn,
Auf dem Hügel 71,
2 Gemini Observatory, Southern Operations Center, Casilla 603, LaSerena, Chile
3 IRFU, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
4 Université Paris Diderot, AIM, Sorbonne Paris Cité, CEA, CNRS, 91191 Gif-sur-Yvette, France
5 Leiden Observatory, Leiden University, Niels Bohrweg 2, 2300 CA Leiden, The Netherlands
6 Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
7 Department of Physics, University of California, Davis, CA 95616, USA
8 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, USA
9 Center for Cosmology and Astro-Particle Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210, USA
10 Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA
11 Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794, USA
12 Department of Physics and Astronomy, Tufts University, 574 Boston Avenue, Medford, MA 02155, USA
13 Department of Physics and Astronomy, York University, 4700 Keele St., Toronto, Ontario MJ3 1P3, Canada
14 Department of Astronomy, University of Michigan, 1085 S. University Ave, Ann Arbor, MI 48109, USA
Accepted: 26 October 2017
We demonstrate that deep good-seeing VLT/HAWK-I Ks images complemented with g + z-band photometry can yield a sensitivity for weak lensing studies of massive galaxy clusters at redshifts 0.7 ≲ z ≲ 1.1, which is almost identical to the sensitivity of HST/ACS mosaics of single-orbit depth. Key reasons for this good performance are the excellent image quality frequently achievable for Ks imaging from the ground, a highly effective photometric selection of background galaxies, and a galaxy ellipticity dispersion that is noticeably lower than for optically observed high-redshift galaxy samples. Incorporating results from the 3D-HST and UltraVISTA surveys we also obtained a more accurate calibration of the source redshift distribution than previously achieved for similar optical weak lensing data sets. Here we studied the extremely massive galaxy cluster RCS2 J232727.7−020437 (z = 0.699), combining deep VLT/HAWK-I Ks images (point spread function with a 0.′′35 full width at half maximum) with LBT/LBC photometry. The resulting weak lensing mass reconstruction suggests that the cluster consists of a single overdensity, which is detected with a peak significance of 10.1σ. We constrained the cluster mass to M200c/(1015 M⊙) = 2.06−0.26+0.28(stat.) ± 0.12(sys.) assuming a spherical Navarro, Frenk & White model and simulation-based priors on the concentration, making it one of the most massive galaxy clusters known in the z ≳ 0.7 Universe. We also cross-checked the HAWK-I measurements through an analysis of overlapping HST/ACS images, yielding fully consistent estimates of the lensing signal.
Key words: gravitational lensing: weak / galaxies: clusters: individual: RCS2 J232727.7−020437
© ESO 2018
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