Disney's (1976) suggestion is reexamined that selection effects dominate Fish's (1964) law concerning the potential energy-mass relation for elliptical galaxies and Freeman's (1970) law concerning the extrapolated central surface brightness of disk galaxies. It is found that selection effects may indeed have influenced the samples discussed by Fish and Freeman, but not in the sense described by Disney. In particular, it is argued that the data set does not show a bias toward large galaxies, but there is a bias against the faint end of the distribution of central surface brightnesses. It is therefore suggested that the observed paucity of ellipticals and spirals with very high extrapolated central surface brightnesses is probably real. Hence Fish's and Freeman's laws should be reformulated to state that very few elliptical and spiral galaxies have extrapolated central isophotes in B which are brighter than, respectively, 12.0 mag per square arcsec and 19.5 mag per square arcsec.
No takes yet. Share an insight, caveat, or question.
Allen et al. (1979) studied this question.