Precise weak lensing constraints from deep high-resolution K 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, Maruša Bradač, 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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8 Scopus citations

Abstract

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.

Original languageEnglish (US)
Article numberA85
JournalAstronomy and astrophysics
Volume610
DOIs
StatePublished - Feb 1 2018
Externally publishedYes

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Keywords

  • Galaxies: clusters: individual: RCS2 J232727.7-020437
  • Gravitational lensing: weak

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Schrabback, T., Schirmer, M., Van Der Burg, R. F. J., Hoekstra, H., Buddendiek, A., Applegate, D., Bradač, M., Eifler, T., Erben, T., Gladders, M. D., Hernández-Martín, B., Hildebrandt, H., Hoag, A., Klaes, D., Der Linden, A. V., Marchesini, D., Muzzin, A., Sharon, K., & Stefanon, M. (2018). Precise weak lensing constraints from deep high-resolution K s images: VLT/HAWK-I analysis of the super-massive galaxy cluster RCS2 J 232727.7-020437 at z = 0.70. Astronomy and astrophysics, 610, [A85]. https://doi.org/10.1051/0004-6361/201731730