Open AccessThe nature of the dwarf population in Abell 868
Author(s) -
Boyce Peter J.,
Phillipps Steven,
Jones J. Bryn,
Driver Simon P.,
Smith Rodney M.,
Couch Warrick J.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04862.x
Subject(s) - physics , astrophysics , dwarf galaxy , astronomy , elliptical galaxy , population , dwarf galaxy problem , luminosity function , galaxy , brightest cluster galaxy , galaxy cluster , luminosity , interacting galaxy , demography , sociology
We present the results of a study of the morphology of the dwarf galaxy population in Abell 868, a rich, intermediate‐redshift cluster which has a galaxy luminosity function (LF) with a steep faint‐end slope . A statistical background subtraction method is employed to study the colour distribution of the cluster galaxies. This distribution suggests that the galaxies contributing to the faint‐end of the measured cluster LF can be split into three populations: dwarf irregular galaxies (dIrrs) with dwarf elliptical galaxies (dEs) with and contaminating background giant ellipticals (gEs) with . The removal of the contribution of the background gEs from the counts only marginally lessens the faint‐end slope . However, the removal of the contribution of the dIrrs from the counts produces a flat LF . The dEs and the dIrrs have similar spatial distributions within the cluster, except that the dIrrs appear to be totally absent within a central projected radius of about 0.2 Mpc . The number densities of both dEs and dIrrs appear to fall off beyond a projected radius of ≃ 0.35 Mpc. We suggest that the dE and dIrr populations of A868 have been associated with the cluster for similar time‐scales, but evolutionary processes such as ‘galaxy harassment’ tend to fade the dIrr galaxies while having a much smaller effect on the dE galaxies. The harassment would be expected to have the greatest effect on dwarfs residing in the central parts of the cluster.