An X-ray Selected Galaxy Cluster in the Lockman Hole at Redshift 1.753
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.
Keywords
Cite
@article{arxiv.1010.0688,
title = {An X-ray Selected Galaxy Cluster in the Lockman Hole at Redshift 1.753},
author = {J. Patrick Henry and Mara Salvato and Alexis Finoguenov and Nicolas Bouche and Hermann Brunner and Vadim Burwitz and Peter Buschkamp and Eiichi Egami and Natasha Foerster-Schreiber and Sotiria Fotopoulou and Reinhard Genzel and Guenther Hassinger and Vincenzo Mainieri and Manolis Rovilos and Gyula Szokoly},
journal= {arXiv preprint arXiv:1010.0688},
year = {2015}
}
Comments
18 pages, 8 figures, accepted for publication in the Astrophysical Journal