Most models devised to account for the excess galaxies seen in number magnitude counts invoke a large population of low-luminosity galaxies at moderate redshifts (or look-back times). Here we directly investigate the faint end of the luminosity function at moderate |z ( 0.2)| via deep R-band observations of the distant Abell cluster A963 made with the Hitchhiker parallel CCD camera on the WHT. By subtracting a ‘mean field’ component from the observed galaxy counts in the cluster area, we deduce the existence of a large dwarf population in the cluster, which gives rise to a significant excess over the mean, right down to the sample limit at |mR 24.5(MR -16.5)|. The implied dwarf-galaxy luminosity function has a steep slope, |α ~ -1.8|, in line with recent work on nearby clusters.
No takes yet. Share an insight, caveat, or question.
Driver et al. (1994) studied this question.