The unveiling of the newly discovered vela supercluster

Abstract

Multi-object spectroscopic observations of high density galaxy concentrations were obtained between 2012 and 2014 with SALT, using the multi-object spectrometer (MOS) of the Robert Stobie Spectograph (RSS) on SALT. The goal was to find the missing clusters in an earlier identified extended galaxy overdensity centered at 18000 km s-1 located at low Galactic latitudes in Vela. Reliable redshifts could be extracted for 80% of the targeted, highly-obscured galaxies. They were found to have an accuracy of the order of σ 150 km s-1. Of the 13 observed fields, ten revealed clear signatures of galaxy clusters. The majority of the clusters form part of the Vela overdensity. Their distribution also confirmed our suspicion that the Vela overdensity is even more extended and seems to straddle the Galactic Plane. Subsequent multi-fibre spectroscopy with AAOmega+2dF on the Australian Telescope confirmed that these clusters are embedded in a gigantic overdensity of about 20°×20° on the sky. The overdensity and its clusters show strong similarities to massive superclusters such as the Shapley Supercluster. This previously unknown Vela Supercluster may well constitute an additional missing piece of the puzzle in solving the various contradictory (residual) bulk flow results given its location on the sky. Show more