Abstract:
The time evolution of galactic luminosity in the framework of the Hoyle-Narlikar (1964, 1974) (HN) cosmology with a variable gravitational constant G is investigated. The luminosity evolution with redshift is studied for both black-body and power-law sources. The G varying HN cosmological models are seen to predict systematically higher luminosities for galaxies at earlier epochs. For thermal black-body sources the increase in infrared K-band luminosity is estimated to be about 1.5 mag for a redshift of z of about 1. Also, the higher temperatures at earlier epochs implied by these models would make the distant galaxies appear bluer. For sources with power-law spectra the magnitude changes are even larger. There is some measure of observational support for the above theoretical predictions.
