Astronomers have completed the first detailed mapping of the Vela Supercluster, a massive and previously obscured structure located behind the Milky Way.
The research, published on the preprint server arXiv on March 10, reveals that the supercluster is larger and more massive than previously understood, making it one of the largest structures in the nearby universe.
Discovery and Methodology
The Vela Supercluster is located in a region known as the "Zone of Avoidance," where dust clouds and stars within the disk of the Milky Way have historically blocked visible light from reaching Earth-based telescopes. The supercluster was originally discovered in 2016, but its full scale had remained unknown.
To map the structure, an international team of scientists used a hybrid technique combining multiple types of galaxy measurements. The team analyzed over 65,000 existing galaxy distance measurements from the CosmicFlows catalogue and added more than 8,000 new galaxy redshift observations. Redshifts indicate how fast galaxies are moving away from Earth due to the expansion of the universe.
Crucial observations came from the Southern African Large Telescope and the MeerKAT radio telescope. MeerKAT’s radio observations detected hydrogen gas emissions, which can penetrate dust, enabling the visibility of galaxies that are otherwise obscured.
Key Findings
- Location: The Vela Supercluster is located approximately 800 million light-years from Earth.
- Size: It spans an estimated 300 million light-years.
- Mass: The structure contains a mass equivalent to about 30 million billion (or 30 quadrillion) suns.
- Composition: The supercluster includes at least 20 galaxy clusters, each containing hundreds or thousands of galaxies. The majority of its mass is distributed into two dense cores that are moving toward each other.
- Comparison: Its mass is comparable to that of the Shapley Supercluster. Its gravitational influence may surpass that of other major structures, including the Laniakea Supercluster (which contains the Milky Way) and the Great Attractor.
"Its gravitational influence may surpass that of other major structures, including the Laniakea Supercluster."
Significance
Former UCT doctoral student Sambatriniaina Rajohnson noted that the mapping helps complete the map of the nearby universe, revealing a major gravitational influence that was previously hidden.
Renee Kraan-Korteweg, emeritus professor at UCT’s Department of Astronomy, stated that the findings confirmed suspicions held for over a decade regarding the role of the structure in cosmic flows, including those affecting Earth’s Local Group of galaxies.
The team has proposed naming the structure the "Vela-Banzi" supercluster. The word "Banzi" is derived from the Xhosa language and means "revealing widely," reflecting its emergence as one of the largest known structures in the nearby cosmos.