Possibility of a large evolutionary correction to the magnitude-redshift relation

Galactic evolution may be rapid enough to reconcile the observed magnitude-redshift relation with cosmological models of acceptably great age and low density, in spite of recent evidence to the contrary. Previous treatments of this subject have suffered from use of wrong quantities as the evolutionary correction, and from lack of generality in galactic models. A range of giant elliptical galaxies can be synthesized which are compatible with the available photometry, including Oke and Sandage's (1968) observations of a slow rate of change of color B-V. One such model galaxy is discussed which evolves sufficiently rapidly at short wavelengths to provide an evolutionary correction of several tenths of a magnitude at redshift 0.46.