1. AN X-RAY-SELECTED GALAXY CLUSTER IN THE LOCKMAN HOLE AT REDSHIFT 1.753
- Author
-
P. Buschkamp, Manolis Rovilos, Gyula P. Szokoly, Hermann Brunner, Alexis Finoguenov, Reinhard Genzel, Vincenzo Mainieri, Sotiria Fotopoulou, Natasha Foerster-Schreiber, J. Patrick Henry, Mara Salvato, Nicolas Bouché, Vadim Burwitz, Eiichi Egami, and Guenther Hassinger
- Subjects
Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Infrared ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Galaxy ,Redshift ,Photometry (optics) ,Stars ,Space and Planetary Science ,Astrophysics::Solar and Stellar Astrophysics ,Surface brightness ,Brightest cluster galaxy ,Galaxy cluster ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We have discovered an X-ray selected galaxy cluster with a spectroscopic redshift of 1.753. The redshift is of the brightest cluster galaxy (BCG), which is coincident with the peak of the X-ray surface brightness. We also have concordant photometric redshifts for seven additional candidate cluster members. The X-ray luminosity of the cluster is 3.68 +/- 0.70 x 10^43 erg s^-1 in the 0.1 - 2.4 keV band. The optical/IR properties of the BCG imply its formation redshift was ~5 if its stars formed in a short burst. This result continues the trend from lower redshift in which the observed properties of BCGs are most simply explained by a monolithic collapse at very high redshift instead of the theoretically preferred gradual hierarchical assembly at later times. However the models corresponding to different formation redshifts are more clearly separated as our observation epoch approaches the galaxy formation epoch. Although our infrared photometry is not deep enough to define a red sequence, we do identify a few galaxies at the cluster redshift that have the expected red sequence photometric properties., 18 pages, 8 figures, accepted for publication in the Astrophysical Journal
- Published
- 2010