Cluster membership of Seyfert galaxies

Extract

I would like to comment on very preliminary results concerning the cluster membership of Seyfert galaxies. Two years ago van den Bergh stated in a discussion of the bright classical Seyfert galaxies that these objects were mainly field galaxies. We extend this discussion to about seventy objects in the list of Drs Khachikian and Weedman (Astrophys. J., 192, 581, 1974). By a cross correlation of this list with Dr Abell's catalogue of rich clusters taking account both of the positions in the sky and the distances of the objects, we find only two certain cluster members - the well-known case NGC 1275 in the Perseus cluster and Markarian 298 in the Hercules cluster - and three probable or possible other cluster members. Taking into account the fact that only some fifty objects of Khachikian and Weedman fall within the distance range of the Abell catalogue, we find that only a few per cent of the Seyfert galaxies are members of Abell clusters. Within a factor of two, this percentage is the same as the percentage of cluster galaxies relative to all galaxies. Therefore, this result does not point to a pronounced field membership of the Seyfert galaxies.