A Definitive Optical Detection of a Supercluster at Z ~ 0.91
Abstract
We present the results from a multiband optical imaging program that has definitively confirmed the existence of a supercluster at z~0.91. Two massive clusters of galaxies, Cl 1604+4304 at z=0.897 and Cl 1604+4321 at z=0.924, were originally observed in the high-redshift cluster survey of Oke, Postman, & Lubin. They are separated by 4300 km s-1 in radial velocity and 17' on the plane of the sky. Their physical and redshift proximity suggested a promising supercluster candidate. Deep BRi imaging of the region between the two clusters indicates a large population of red galaxies. This population forms a tight, red sequence in the color-magnitude diagram at (R-i)~1.4. The characteristic color is identical to that of the spectroscopically confirmed early-type galaxies in the two member clusters. The red galaxies are spread throughout the 5 h-1 Mpc region between Cl 1604+4304 and Cl 1604+4321. Their spatial distribution delineates the entire large-scale structure with high concentrations at the cluster centers. In addition, we detect a significant overdensity of red galaxies directly between Cl 1604+4304 and Cl 1604+4321 which is the signature of a third, rich cluster associated with this system. The strong sequence of red galaxies and their spatial distribution clearly indicate that we have discovered a supercluster at z~0.91.
- Publication:
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The Astrophysical Journal
- Pub Date:
- March 2000
- DOI:
- 10.1086/312518
- arXiv:
- arXiv:astro-ph/0001166
- Bibcode:
- 2000ApJ...531L...5L
- Keywords:
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- COSMOLOGY: OBSERVATIONS;
- GALAXIES: CLUSTERS: INDIVIDUAL: ALPHANUMERIC: CL 1604+4304;
- GALAXIES: CLUSTERS: INDIVIDUAL: ALPHANUMERIC: CL 1604+4321;
- COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE;
- Astrophysics
- E-Print:
- Accepted for publication in Astrophysical Journal Letters. 13 pages, including 5 figures