The ROSAT deep survey. VII. RX J105343+5735: A massive cluster at z=1.263
Abstract
The eastern lobe of the unusual double-lobed extended X-ray source RX J105343+5735 is confirmed to be a massive cluster at high redshift. Deep optical and near-infrared imaging show an overdensity of galaxies in both X-ray lobes, including a significant excess of red galaxies (R-K>5.3) with colors typical of elliptical galaxies at z>1. We have used new photometry to place better constraints on the redshifts of the cluster galaxies. A Keck NIRSPEC spectrum of one of the bright central galaxies in the eastern lobe shows a narrow Hα emission line at 1.485 microns, yielding a redshift of 1.263. The [O Ii] lambda 3727 Å line from the gravitationally lensed arc is also detected, giving a redshift of 2.577 for the lensed galaxy and confirming prior measurements. The improbability of chance alignment and similarity of colors for the galaxies in the two X-ray lobes are consistent with the western lobe also being at z=1.26. The system may thus represent a pair of clusters in the process of merging.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 2001
- DOI:
- Bibcode:
- 2001A&A...377..778T
- Keywords:
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- GALAXIES: CLUSTERS;
- DISTANCES AND REDSHIFTS;
- COSMOLOGY: OBSERVATIONS;
- GRAVITATIONAL LENSING;
- INFRARED: GALAXIES;
- X-RAYS: GALAXIES