CAPE TOWN, March 12 (Xinhua) -- Astronomers have revealed the true extent of a vast galaxy supercluster hidden behind the Milky Way, showing that the Vela Supercluster is far larger and more massive than previously thought.
The discovery was released Thursday by scientists at the University of Cape Town (UCT) and international collaborators, shedding new light on one of the largest structures in the nearby universe and helping explain large-scale motions of galaxies across hundreds of millions of light-years.
Astronomers said in a statement that the enormous concentration of galaxies had long remained largely hidden behind dense clouds of dust and billions of stars in the Milky Way's disk, in a region known as the "Zone of Avoidance."
The international research team developed a hybrid technique combining multiple types of galaxy measurements. The method used galaxy redshifts, which show how fast galaxies are moving away as the universe expands, together with galaxy distance and motion measurements that reveal how gravity influences their movement through space.
By combining more than 65,000 galaxy distance measurements from the CosmicFlows catalogue with over 8,000 newly observed galaxy redshifts, researchers reconstructed the distribution of matter hidden behind the Milky Way.
Observations from the Southern African Large Telescope and the MeerKAT radio telescope have allowed researchers to detect galaxies deep inside the most obscured regions of the sky. MeerKAT's radio observations detected hydrogen gas at wavelengths that passed through dust, revealing galaxies that optical telescopes could not easily see.
The analysis showed the Vela Supercluster lies about 800 million light-years away and stretches across roughly 300 million light-years. It contains an estimated mass equivalent to about 30 million billion suns, rivaling the well-known Shapley Supercluster, long considered one of the most massive structures in the nearby universe.
The system appeared complex, with two dense cores moving toward each other, and its gravitational influence may exceed that of other major structures such as the Laniakea Supercluster -- the supercluster that includes our own galaxy -- and the Great Attractor.
Renee Kraan-Korteweg, emeritus professor in the UCT's Department of Astronomy and one of the researchers who led the study, said the findings confirmed suspicions developed over more than a decade.
"I am truly exhilarated that the data gathered by my group could be successfully incorporated into this novel methodology," she said. "It has finally confirmed the prominence of the Vela-Banzi supercluster -- something I suspected more than a decade ago -- and shows that it plays an important role in the large-scale cosmic flows in our region of the Universe, including our own Local Group of galaxies."
Researchers noted that mapping the structure will help scientists better understand "cosmic flows" -- the vast gravitational movements of galaxies across space.
Former UCT doctoral student Sambatriniaina Rajohnson, who is part of the international collaboration, said the discovery filled a major gap in astronomers' map of the nearby universe.
"This discovery helps complete our map of the nearby Universe. For the first time, we can clearly see one of the major gravitational players hidden behind our own galaxy," she said.
The team also proposed a locally inspired name, "Vela-Banzi," for the structure, which is derived from the Xhosa language and means "revealing widely," reflecting how the enormous supercluster is emerging from behind the Milky Way as one of the largest known structures in the nearby cosmos. Enditem
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