A SPECTROSCOPICALLY CONFIRMED X-RAY CLUSTER AT z = 1.62 WITH A POSSIBLE COMPANION IN THE SUBARU/XMM-NEWTON DEEP FIELD
- Institute for the Physics and Mathematics of the Universe, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8583 (Japan)
- Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, D-8574 Garching bei Muenchen (Germany)
- Department of Astronomy, Kyoto University, Kyoto 606-8502 (Japan)
We report on a confirmed galaxy cluster at z = 1.62. We discovered two concentrations of galaxies at z {approx} 1.6 in the Subaru/XMM-Newton deep field based on deep multi-band photometric data. We made a near-IR spectroscopic follow-up observation of them and confirmed several massive galaxies at z = 1.62. One of the two is associated with an extended X-ray emission at 4.5{sigma} on a scale of 0.'5, which is typical of high-z clusters. The X-ray detection suggests that it is a gravitationally bound system. The other one shows a hint of an X-ray signal, but only at 1.5{sigma}, and we obtained only one secure redshift at z = 1.62. We are not yet sure if this is a collapsed system. The possible twins exhibit a clear red sequence at K < 22 and seem to host relatively few number of faint red galaxies. Massive red galaxies are likely old galaxies-they have colors consistent with the formation redshift of z{sub f} = 3, and a spectral fit of the brightest confirmed member yields an age of 1.8{sup +0.1}{sub -0.2} Gyr with a mass of 2.5{sup +0.2}{sub -0.1} x 10{sup 11} M{sub sun}. Our results show that it is feasible to detect clusters at z > 1.5 in X-rays and also to perform detailed analysis of galaxies in them with the existing near-IR facilities on large telescopes.
- OSTI ID:
- 21451078
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 716; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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