Astronomers from the University of Cape Town (UCT) – working with colleagues from Université Claude Bernard Lyon 1 (France), Swinburne University of Technology (Australia) and the INAF Osservatorio Astronomico di Cagliari (Italy) have mapped a massive structure in the Universe – a huge supercluster, partially obscured from us behind the Milky Way’s ‘Zone of Avoidance.’ This is a region that is about 20 per cent of the night sky – a very large area that contains thick interstellar dust and many dense star fields, creating an extensive ‘blind spot’ from observations done with optical telescopes, as noted in a study of the University of Cape Town. Using a new method of hybrid mapping – an approach that brings together data on galaxy redshift with radio waves over long distances using the MeerKAT telescope, scientists have discovered the Vela Supercluster. The supercluster spans 300 million light-years and is located 800 million light-years from us, helping fill in a large missing piece to our understanding of the universe.
Hidden Vela Supercluster found behind Milky Way dust
According to the study published by the University of Cape Town, the discovery of the Vela Supercluster, named ‘Vela-Banzi,’ serves as a critical node of evidence related to the explanation of ‘cosmic flows,’ the large-scale movement of galaxies caused by their mutual attraction via intense gravitational pull; indeed, as a result of the presence of significant amounts of dust and gas within the Milky Way’s disk, the actual distribution of mass within this region was obscured. To confirm the presence of this supercluster and its effect on the motion of matter in our local portion of the universe, scientists employed radio distance measurements to penetrate this obstruction.
Radio waves revealed a cosmic giant
The term ‘Zone of Avoidance’ refers to the portion of the sky obscured by our own galaxy’s plane, and since its inception, astronomers have been unable to see the entire structure of the local universe within this portion of the sky. In this case, by utilising radio wavelengths instead of optical wavelengths to search for the signatures of galaxies obscured by the Milky Way, the researchers were able to create a three-dimensional reconstruction that demonstrates that the Vela structure is as massive and influential as other well-known structures, such as the Shapley Supercluster.
The role of superclusters in galactic evolution
To map the ‘Cosmic Web’ – the large-scale network of filaments and voids that form the universe, it is important to understand the Vela Supercluster as it is one of the nodes in this web of superclusters that pull in surrounding matter and ultimately influence how galaxies evolve over the course of billions of years. The addition of this great structure to the map allows astronomers to create a better model of the gravitational forces acting on the Milky Way and other galaxies that are close by. This new structure gives us a greater understanding of the expansion and formation of the local universe and fills in a significant gap that has existed since the beginning of extragalactic astronomy.
