Hidden by the Milky Way: Vela supercluster much larger than thought
Super galaxy clusters are among the largest structures in the universe. Now, a particularly large one has been measured, hidden from us behind the Milky Way.
The local universe and its superclusters
(Image: JĂ©rĂ´me LĂ©ca, RSA Cosmos, St Etienne, France)
A gigantic structure of countless galaxies, hidden by the Milky Way, is much larger and more massive than previously assumed. This is what observations with two observatories in South Africa have revealed, significantly refining our understanding of the Vela supercluster. This collection of several galaxy clusters is therefore comparable in size to the Shapley supercluster and combines more mass than Laniakea. This is the supercluster in which the Milky Way is located. At about 800 million light-years away from us, Vela is 300 million light-years long and contains about 30 million billion solar masses, explains the research group. They have given the structure the nickname “Vela-Banzi”, the suffix meaning “revealing widely” in the South African language isiXhosa.
More massive than our own supercluster
The Vela supercluster, or super galaxy cluster, is particularly difficult to research because, from our perspective, it is located directly behind the Milky Way. Its stars and interstellar dust prevent us from getting a good view behind our home galaxy in about 20 percent of the night sky. This also makes it difficult to gain a comprehensive understanding of our neighborhood and larger structures in the universe. For their work, the research group led by Amber Hollinger from the Université Claude Bernard Lyon 1 analyzed more than 65,000 distance measurements to galaxies and 8,000 to redshift. The data comes from the Southern African Large Optical Telescope (SALT) and the MeerKAT radio telescope.
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The analysis revealed that Vela has a complex internal structure and consists of two dense cores moving towards each other, the team explains. With their enormous mass, superclusters like Vela influence large-scale shifts of matter in the universe. The analysis also completes our picture of the local universe, which therefore consists of nine such superclusters. Our own was first described in 2014, the two closest being Perseus and Pisces. The new description of the Vela supercluster has been submitted for publication in the journal Astronomy & Astrophysics.
(mho)
