Published: Sat, July 15, 2017
Science | By Hubert Green

Superclusters of galaxies discovered by Indian Astronomers, named as "Saraswati"

Superclusters of galaxies discovered by Indian Astronomers, named as

Researchers from the Inter University Centre for Astronomy & Astrophysics (IUCAA), Indian Institute of Science Education and Research (IISER) and members of two other Indian universities have called this supercluster "one of the largest known structures in the nearby areas of the universe".

A team of six astronomers from Pune, Jamshedpur and Thodupuzha in Kerala discovered the massive supercluster, which resembles a wall of galaxies spanning over 600 million light years, an unimaginably vast region of the universe.

The big cluster of galaxies, located about 4 million light years away from Earth, has been named Saraswati after the Goddess and means ever-flowing stream with many pools. The mass of the cluster extends over the scale of 600 million light years. "It is true that the balance between dark matter and dark energy can produce large structures, but a supercluster of this size does present an enigma", said Raychaudhury. "Even the Shapley is about 8-10 times closer", said Somak Raychaudhury, Director of IUCAA and one of the authors of the paper being published in the latest issue of The Astrophysical Journal.

A Supercluster is a chain of galaxies and galaxy clusters, bound by gravity, often several hundred times bigger than clusters of galaxies.

. Only a few large superclusters of this magnitude have been discovered, such as the Shapley Concentration. This raises questions about the formation of large structures and the nature of the universe, astronomers say. There are an estimated 10 million superclusters in the observable universe. "This supercluster is clearly embedded in a large network of cosmic filaments traced by clusters and large voids", Bagchi said.

Most models of cosmic evolution, including "cold dark matter" models, fail to to predict the formation of superstructures like Saraswati.

In recent years, the discovery of the present-day universe being dominated by "Dark Energy", which behaves very differently from gravitation, might play a role in the formation of these structures. The Saraswati supercluster could challenge this premise, because it was formed so early and building such a big structure far back might have been hard. In modern India, Saraswati is worshipped as the goddess of knowledge. The work is expected to help better understand matter density clusters that had been formed billions of years ago.

The team analyzed the data from Sloan Digital Sky Survey, a large spectroscopic survey of different galaxies. The Milky Way is a part of a local group, which has around 50 galaxies in it.

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