The Light Travel Time and the Evolutionary Correction to Magnitudes of Distant Galaxies.

Abstract

view Abstract Citations (108) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Light Travel Time and the Evolutionary Correction to Magnitudes of Distant Galaxies. Sandage, Allan Abstract Equations are derived for the difference r between the time of emission, ti, and time of reception on the earth, t0, of light from distant galaxies This difference is the travel time for light from the galaxy in question. The time is strongly dependent on the model of the universe. Closed equations for r are given for evolving models of the Friedman type with k = + 1,0, -1, and for the steady-state model. Numerical results are shown in Tables 2 and 3 for various values of the redshift and the deceleration parameter. The change in luminosity of E and 80 galaxies in the time r is discussed. Any change which occurs must be considered when observational data on redshifts and apparent magnitudes are used to determine qo A simple model of the stellar content of E galaxies is given to illustrate the method of computation of the evolutionary correction From this model it is found that E galaxies in the cluster 3C 295, whose redshift is AX/X0 = 0 461, have become fainter by 0 38 mag in the light-travel time. This computation starts from Baum's unpublished value of qo = + 1 and assumes that he made no correction for evolution. Correcting the observed magnitudes for evolution by the model gives a true value for qi of about +02. The large uncertainty of this result is discussed Publication: The Astrophysical Journal Pub Date: November 1961 DOI: 10.1086/147218 Bibcode: 1961ApJ...134..916S full text sources ADS |