Redshifts distribution in A262

Abstract

Galaxy clusters are the largest virialized systems in the Universe containing a collection of galaxies of dierent redshifts. The redshift distribution of galaxies in galaxy clusters is concentrated at a certain redshift range which remarkably tells us that only the galaxies in a certain radial range belong to the galaxy cluster. This leads to a boundary estimation of the cluster. Background and foreground systems are represented by a histogram that determines whether some of the galaxies are too far or too high in redshift to be counted as the member of the cluster. With the recent advances in multibre spectroscopy it has become possible to perform detailed analysis of the redshift distribution of several galaxy clusters in the Abell Catalogue. This has given rise to signicantly improved estimates of cluster membership, extent and dynamical history. Here we present a spectroscopic analysis of the galaxy cluster A262. We nd 55 galaxies fall within z = 0.0143 and 0.0183 with velocity range 4450 { 5300 km/s, and are therefore members of the cluster. We derived a new mean redshift of z = 0:016173 0:000074 (4852 22 km/s) for the system of which we compare with our neutral hydrogen (HI) detection which peaks at 4970 0:5 km/s. It is found that the distribution of HI tends to be located at the edge of the cluster since most of spiral rich galaxies were away from cluster center.