Journal Article

The massive galaxy cluster XMMU J1230.3+1339 at <i>z ∼ 1</i>: colour–magnitude relation, Butcher–Oemler effect, X-ray and weak lensing mass estimates*

M. Lerchster, S. Seitz, F. Brimioulle, R. Fassbender, M. Rovilos, H. Böhringer, D. Pierini, M. Kilbinger, A. Finoguenov, H. Quintana and R. Bender

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 411, issue 4, pages 2667-2694
Published in print March 2011 | ISSN: 0035-8711
Published online March 2011 | e-ISSN: 1365-2966 | DOI:
The massive galaxy cluster XMMU J1230.3+1339 at z ∼ 1: colour–magnitude relation, Butcher–Oemler effect, X-ray and weak lensing mass estimates*

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We present results from the multiwavelength study of XMMU J1230.3+1339 at z∼ 1. We analyse deep multiband wide-field images from the Large Binocular Telescope (LBT), multi-object spectroscopy observations from VLT, as well as space-based serendipitous observations, from the GALEX and Chandra X-ray observatories. We apply a Bayesian photometric redshift code to derive the redshifts using the far-UV (FUV), near-UV (NUV) and the deep U, B, V, r, i, z data. We make further use of spectroscopic data from FORS2 to calibrate our photometric redshifts, and investigate the photometric and spectral properties of the early-type galaxies. We achieve an accuracy of ▵z/(1 +z)= 0.07 (0.04) and the fraction of catastrophic outliers is η= 13 (0) per cent, when using all (secure) spectroscopic data, respectively. The iz against z colour–magnitude relation of the photo-z members shows a tight red sequence with a zero-point of 0.935 mag, and slope equal to −0.027. We observe evidence for a truncation at the faint end of the red-cluster-sequence and the Butcher–Oemler effect, finding a fraction of blue galaxies fb≈ 0.5. Further, we conduct a weak lensing analysis of the deep 26 × 26 arcmin r-band lbc image. The observed shear is fitted with a Single-Isothermal-Sphere and a Navarro–Frenk–White model to obtain the velocity dispersion and the model parameters, respectively. Our best-fitting values are, for the velocity dispersion σSIS= 1308 ± 284 km s−1, concentration parameter c= 4.0+14−2 and scale radius rs= 345+50−57 kpc. From a 38 ks Chandra X-ray observation we obtain an independent estimate of the cluster mass. In addition, we create a signal-to-noise ratio (S/N) map for the detection of the matter mass distribution of the cluster using the mass-aperture technique. We find excellent agreement of the mass concentration identified with weak lensing and the X-ray surface brightness. Combining our mass estimates from the kinematic, X-ray and weak lensing analyses we obtain a total cluster mass of Mtot200= (4.56 ± 2.3) × 1014 M. This study demonstrates the feasibility of ground-based weak lensing measurements of galaxy clusters up to z∼ 1.

Keywords: gravitational lensing; galaxies: clusters: individual: XMMU J1230.3+1339; galaxies: fundamental parameters; X-rays: galaxies: clusters

Journal Article.  15173 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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