Abstract
We report the discovery of XMMXCS J2215.9-1738, a massive galaxy cluster at z = 1.45, which was found in the XMM Cluster Survey. The cluster candidate was initially identified as an extended X-ray source in archival XMM data. Optical spectroscopy shows that six galaxies within a ~60'' diameter region lie at z = 1.45 ± 0.01. Model fits to the X-ray spectra of the extended emission yield kT = 7.4+2.7-1.8 keV (90% confidence); if there is an undetected central X-ray point source, then kT = 6.5+2.6-1.8 keV. The bolometric X-ray luminosity is LX = 4.4+0.8-0.6 × 1044 ergs s-1 over a 2 Mpc radial region. The measured TX, which is the highest for any known cluster at z > 1, suggests that this cluster is relatively massive for such a high redshift. The redshift of XMMXCS J2215.9-1738 is the highest currently known for a spectroscopically confirmed cluster of galaxies.
Original language | English |
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Pages (from-to) | L13-L16 |
Journal | The Astrophysical Journal |
Volume | 646 |
Issue number | 1 |
Early online date | 14 Jul 2006 |
DOIs | |
Publication status | Published - 20 Jul 2006 |