The Redshifts of Extragalactic Objects

Abstract

We review the evidence for a general shift-distance law for galaxies. This is shown directly by a redshift-distance diagram recently prepared by Sandage and Tammann for Sc I galaxies. The distances are measured from H II region diameters and from the diameters of the Sc 1 galaxies themselves for the more distant systems. We also show the redshift-apparent magnitude diagrams for several objects which are identifiable over a large range in distance and which prove to have a small range in absolute magnitude: these are supernovae of type I (Kowal and Sargent, 1973, unpublished), brightest cluster galaxies (Sandage, 1972a), and radio galaxies (excluding N-type galaxies) (Sandage, 1972b). Plots of redshift versus angular size for brightest cluster galaxies (Sandage, 1972c) also have the correct slope for this to be a distance effect. In summary, the tightness of the correlations for the various diagrams listed implies that there is a very close correlation between distance and redshift for galaxies out to at least z = Δλ/λ~0.2 and that there is no evidence for redshift anomalies among the objects in these diagrams.