Abstract
We present the results of a study of the morphology of the dwarf galaxy population in Abell 868, a rich, intermediate-redshift (z = 0.154) cluster which has a galaxy luminosity function (LF) with a steep faint-end slope (alpha = -1.26 +/- 0.05). A statistical background subtraction method is employed to study the B - R 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 B - R < 1.4; dwarf elliptical galaxies (dEs) with 1.4 <less than or equal to> B - R less than or equal to 2.5; and contaminating background giant ellipticals (gEs) with B - R > 2.5. The removal of the contribution of the background gEs from the counts only marginally lessens the faint-end slope (alpha = -1.22 +/- 0.16). However, the removal of the contribution of the dIrrs from the counts produces a flat LF (alpha = -0.91 +/- 0.16). The dEs and the dIrrs have similar spatial distributions within the cluster, except that the dh-rs appear to be totally absent within a central projected radius of about 0.2 Mpc (H-0 = 75 km s(-1) Mpc(-1)). The number densities of both dEs and dIrrs appear to fall off beyond a projected radius of similar or equal to 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.
Original language | English |
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Pages (from-to) | 277-282 |
Number of pages | 6 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 328 |
Publication status | Published - 21 Nov 2001 |
Keywords
- methods : data analysis
- galaxies : clusters : general
- galaxies : clusters : individual : Abell 868
- galaxies : dwarf
- galaxies : evolution
- galaxies : luminosity function, mass function
- GALAXY LUMINOSITY FUNCTION
- RICH CLUSTERS
- REDSHIFT SURVEY
- LOCAL GROUP
- DENSITY
- DISTRIBUTIONS
- PHOTOMETRY
- HARASSMENT
- EVOLUTION