Luminosity segregation in three clusters of galaxies (A119, A2443, A2218)

Abstract

We use deep wide-field V-band imaging obtained with the Wide Field Camera at the prime focus of the Issac Newton Telescope to study the spatial and luminosity distribution of galaxies in three low redshift (0.04 < z < 0.2) clusters: Abell 119, Abell 2443 and Abell 2218. The absolute magnitude limits probed in these clusters are M V - 5 log h 0.7 = -13.3, -15.4 and -16.7 mag, respectively. The galaxy population, at all luminosities, along the line-of-sight to the clusters can be described by the linear combination of a King profile and a constant surface density of field galaxies. We find that, for these three clusters, the core radius is invariant with intrinsic luminosity of the cluster population to the above limits and thus there is no evidence for luminosity segregation in these clusters. The exception is the brightest galaxies in A2218 which exhibit a more compact spatial distribution. We find that the total projected luminosity distribution (within 1 h -1 0.7 Mpc of the cluster centre) can be well represented by a single Schechter function with moderately flat faint-end slopes: a = -1.22 +0.07 -0.06 (A119), a = -1.11 +0.10 -0.09 (A2443) and α = -1.14 +0.08 -0.07 (A2218). We perform a geometric deprojection of the cluster galaxy population and confirm that no 'statistically significant' evidence of a change in the shape of the luminosity distribution with cluster-centric radius exists. Again, the exception being A2218 which exhibits a core region with a flatter faint-end slope.