Spectroscopy of galaxies in distant clusters. III. The population of Cl 0024+1654

Journal Article · Mon Jul 01 04:00:00 EDT 1985 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/163276· OSTI ID:5307584

Dressler, A; Gunn, J E; Schneider, D P

We present the results of a spectroscopic study of 38 objects in the field of the very rich, concentrated cluster Cl 0024+1654 at a redshift of z = 0.391. All of the red galaxies and 14 of the 22 blue objects are found to be cluster members. The spectra of the blue cluster members are very similar to those of low-redshift spirals, suggesting that these distant galaxies are also undergoing protracted periods of star formnation. These data support Butcher and Oemler's suggestion that this cluster provides evidence for evolution of the blue population of clusters, to the extent that no low-redshift, concentrated cluster is known to have such a large population of blue galaxies. Three of the blue cluster members have spectra typical of active galactic nuclei, which lends support to the proposal of Dressler and Gunn that such activity was much more common only 4--5 x 10/sup 9/ yr ago. On the other hand, no '' starburst'' galaxies like those in the 3C 295 cluster have been found. We describe a technique for finding emission-line galaxies at a known redshift by imaging through a narrow-band filter centered on redshifted (OII) lambda3727 and demonstrate that this procedure detects (OII) emission at a level consistent with our spectroscopic measurements. With this technique, we have found other examples of blue galaxies with (OII) emission, and the strongest of these was confirmed to be an AGN by subsequent spectroscopic measurement. This method is extremely efficient because it covers the entire field at once and will be particularly valuable for work on higher redshift clusters where even multislit spectroscopy is difficult at the present time.

• Research Organization: Mount Wilson and Las Campanas Observatories of the Carnegie Institution of Washington
• OSTI ID: 5307584
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 294:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COLOR
ELECTROMAGNETIC RADIATION
EMISSION SPECTRA
GALACTIC EVOLUTION
GALAXIES
GALAXY CLUSTERS
INFRARED RADIATION
INFRARED SPECTRA
MAPS
MORPHOLOGY
NEAR INFRARED RADIATION
OPTICAL PROPERTIES
ORGANOLEPTIC PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
RADIATIONS
RED SHIFT
SPECTRA
STAR EVOLUTION
VISIBLE SPECTRA