Galaxy clusters in the Vela Supercluster – I. Deep NIR catalogues

Abstract

ABSTRACT We present six deep Near-InfraRed (JHKs) photometric catalogues of galaxies identified in six cluster candidates (VC02, VC04, VC05, VC08, VC10, and VC11) within the Vela Supercluster (VSCL) as part of our efforts to learn more about this large supercluster, which extends across the zone of avoidance (ℓ = 272.°5 ± 20°, b = ±10°, at cz ∼ 18 000 km s−1). The observations were conducted with the InfraRed Survey Facility (IRSF), a 1.4-m telescope situated at the South African Astronomical Observatory (SAAO) in Sutherland. The images in each cluster cover $\sim 80{{\ \rm per\ cent}}$ of their respective Abell radii. We identified a total number of 1715 galaxies distributed over the six cluster candidates, of which only $\sim 15{{\ \rm per\ cent}}$ were previously known. We study the structures and richnesses of the six clusters out to the cluster-centric completeness radius of rc < 1.5 Mpc and magnitude completeness limit of $K_s^o\lt 15{_{.}^{\rm m}}5$, using their iso-density contour maps and radial density profiles. The analysis shows VC04 to be the richest of the six. It is a massive cluster comparable to the Coma and Norma clusters, although its velocity dispersion, σv = 455 km s−1, seems rather low for a rich cluster. VC02 and VC05 are found to be relatively rich clusters while VC08 is rather poor. Also, VC05 has the highest central number density among the six. VC11 is an intermediate cluster that contains two major subclusters while VC10 has a filament-like structure and is likely not to be a cluster after all.