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The extension of the Hubble diagram. I. New redshifts and BVR photometry of remote cluster galaxies, and an improved richness correction

Sandage, Allan and Kristian, Jerome and Westphal, James A. (1976) The extension of the Hubble diagram. I. New redshifts and BVR photometry of remote cluster galaxies, and an improved richness correction. Astrophysical Journal, 205 (2). pp. 688-695. ISSN 0004-637X. https://resolver.caltech.edu/CaltechAUTHORS:20150709-065058210

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Abstract

Absorption-line redshifts for 37 galaxies in 31 remote clusters have been measured with the new sky-subtracting prism spectrograph, using an SIT television detector with digital readout. Twenty-five galaxies in the sample have redshifts larger than z = 0.20. New photoelectric BVR photometry has been obtained for 16 of the clusters. Magnitudes corrected for aperture effect, K-dimming, galactic absorption, cluster richness, and Bautz-Morgan contrast effect are listed. The data permit an improvement in the statistics of the Hubble diagram to z = 0.28 and a new determination of the dependence of the absolute magnitude of the brightest cluster galaxy on cluster richness. A small correlation with richness is found whose amplitude is 0.20 ± 0.18 mag over all Abell richness classes 0-4. As in previous studies, the shallowness of the correlation requires that if M(l) is governed by a general luminosity function, Φ(M), for fainter members, then the slope of Φ(M) at M(I) must be very steep. The 16 new clusters with photometry have a dispersion in M(l) of 0.26 mag. The dispersion of fully corrected magnitudes for the 65 clusters in the total sample is 0.276 mag. The new points in the Hubble diagram give no indication that the (m, z) relation deviates from the q_0(formal) = + 1 line (i.e. with no evolutionary correction applied), nor that 3C 295 is abnormally bright. The need for more data with z > 0.3 is stressed.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1086/154324DOIArticle
http://adsabs.harvard.edu/abs/1976ApJ...205..688SADSArticle
Additional Information:© 1976 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1975 September 5. This work was supported in part by the National Science Foundation under grant GP-36450 X to the Carnegie Institution of Washington.
Funders:
Funding AgencyGrant Number
NSFGP-36450 X
Subject Keywords:cosmology, galaxies: clusters of, galaxies: redshifts
Issue or Number:2
Record Number:CaltechAUTHORS:20150709-065058210
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150709-065058210
Official Citation:The extension of the Hubble diagram. I. New redshifts and BVR photometry of remote cluster galaxies, and an improved richness correction. Authors: Sandage, A., Kristian, J., & Westphal, J. A. Journal: Astrophysical Journal, Vol. 205, p. 688 - 695
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58816
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:09 Jul 2015 17:04
Last Modified:03 Oct 2019 08:40

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