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arXiv · 1711.00475

Precise weak lensing constraints from deep high-resolution $K_\mathrm{s}$ images: VLT/HAWK-I analysis of the super-massive galaxy cluster RCS2$J$232727.7$-$020437 at $z=0.70$

Tim Schrabback·Mischa Schirmer·Remco F. J. van der Burg·Henk Hoekstra·Axel Buddendiek·Douglas Applegate·Marusa Bradac·Tim Eifler·Thomas Erben·Michael D. Gladders·Beatriz Hernández-Martín·Hendrik Hildebrandt·Austin Hoag·Dominik Klaes·Anja von der Linden·Danilo Marchesini·Adam Muzzin·Keren Sharon·Mauro Stefanon
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Abstract

We demonstrate that deep good-seeing VLT/HAWK-I $K_\mathrm{s}$ images complemented with $g$+$z$-band photometry can yield a sensitivity for weak lensing studies of massive galaxy clusters at redshifts \mbox{$0.7\lesssim z \lesssim 1.1$}, 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 $K_\mathrm{s}$ 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$J$232727.7$-$020437 (\mbox{$z=0.699$}), combining deep VLT/\mbox{HAWK-I} $K_\mathrm{s}$ images (point spread function with a 0\farcs35 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 $10.1\sigma$. We constrained the cluster mass to \mbox{$M_\mathrm{200c}/(10^{15} \mathrm{M}_\odot) =2.06^{+0.28}_{-0.26}(\mathrm{stat.})\pm 0.12 (\mathrm{sys.})$} 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 \mbox{$z\gtrsim 0.7$} 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.

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Tim Schrabback, Mischa Schirmer, Remco F. J. van der Burg, Henk Hoekstra, Axel Buddendiek, Douglas Applegate, Marusa Bradac, Tim Eifler, Thomas Erben, Michael D. Gladders, Beatriz Hernández-Martín, Hendrik Hildebrandt, Austin Hoag, Dominik Klaes, Anja von der Linden, Danilo Marchesini, Adam Muzzin, Keren Sharon, Mauro Stefanon. 2017-11-01. Precise weak lensing constraints from deep high-resolution $K_\mathrm{s}$ images: VLT/HAWK-I analysis of the super-massive galaxy cluster RCS2$J$232727.7$-$020437 at $z=0.70$. https://doi.org/10.1051/0004-6361%2F201731730

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