Volume 507, Number 1, November III 2009
|Page(s)||147 - 157|
|Section||Cosmology (including clusters of galaxies)|
|Published online||01 October 2009|
JKCS 041: a colour-detected galaxy cluster at ~ 1.9 with deep potential well as confirmed by X-ray data
INAF – Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy e-mail: email@example.com
2 Department of Physics, University of Bristol, Tyndall Ave, Bristol BS8 1TL, UK
3 Max-Planck-Institut fur Astronomie, Konigstuhl 17, 69117 Heidelberg, Germany
Accepted: 24 September 2009
We report the discovery of JKCS 041, a massive near-infrared selected cluster of galaxies at ~1.9. The cluster was originally discovered using a modified red-sequence method and also detected in follow-up Chandra data as an extended X-ray source. Optical and near-infrared imaging data alone allow us to show that the detection of JKCS 041 is secure, even in the absence of the X-ray data. We investigate the possibility that JKCS 041 is not a galaxy cluster at z ~ 1.9, and find other explanations unlikely. The X-ray detection and statistical arguments rule out the hypothesis that JKCS 041 is actually a blend of groups along the line of sight, and we find that the X-ray emitting gas is too hot and dense to be a filament projected along the line of sight. The absence of a central radio source and the extent and morphology of the X-ray emission argue against the possibility that the X-ray emission comes from inverse Compton scattering of CMB photons by a radio plasma. The cluster has an X-ray core radius of arcsec (about 300 kpc), an X-ray temperature of keV, a bolometric X-ray luminosity within R500 of (7.6±0.5) 1044 erg s-1, and an estimated mass of M500 = 1014 , the last derived under the usual (and strong) assumptions. The cluster is composed of 16.4 ± 6.3 galaxies within 1.5 arcmin (750 kpc) brighter than K ~ 20.7 mag. The high redshift of JKCS 041 is determined from the detection colour, from the detection of the cluster in a galaxy sample formed by > 1.6 galaxies and from a photometric redshift based on 11-band spectral energy distribution fitting. By means of the latter we find the cluster redshift to be 1.84 < z < 2.12 at 68% confidence. Therefore, JKCS 041 is a cluster of galaxies at ~ 1.9 with a deep potential well, making it the most distant cluster with extended X-ray emission known.
Key words: galaxies: evolution / galaxies: clusters: general / galaxies: clusters: individual: JKCS 041 / cosmology: dark matter / X-rays: galaxies: clusters / methods: statistical
© ESO, 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.