Astronomers find largest-yet galaxy proto-supercluster

An international team of astronomers using the VIMOS instrument of ESO’s Very Large Telescope have uncovered a titanic structure in the early universe. This galaxy proto-supercluster — which they nicknamed Hyperion — is the largest and most massive structure yet found at such a remote time and distance — only 2 billion years after the Big Bang. Image via ESO.

An international team of astronomers, using the European Southern Observatory’s (ESO) Very Large Telescope, haa identified a gigantic supercluster of galaxies forming in the early universe, just 2.3 billion years after the Big Bang.

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A supercluster is a large group of smaller galaxy clusters or galaxy groups- among the largest-known structures of the cosmos.

The newly-discovered structure, which the researchers nicknamed Hyperion after a Titan from Greek mythology due to the immense size and mass of the proto-supercluster, is the largest and most massive structure to be found so early in the formation of the universe. The enormous mass of the proto-supercluster is calculated to be more than one million billion times that of the sun. This titanic mass is similar to that of the largest structures observed in the universe today, but finding such a massive object in the early universe surprised astronomers.

Olga Cucciati of Istituto Nazionale di Astrofisica is the first author of the discovery paper, accepted for publication in the peer-reviewed journal Astronomy & Astrophysics. Cucciati said in a statement:

This is the first time that such a large structure has been identified at such a high redshift, just over 2 billion years after the Big Bang. Normally these kinds of structures are known at lower redshifts, which means when the universe has had much more time to evolve and construct such huge things. It was a surprise to see something this evolved when the universe was relatively young!

Light reaching Earth from extremely distant galaxies took a long time to travel, giving us a window into the past when the universe was much younger. This wavelength of this light has been stretched by the expansion of the universe over its journey, an effect known as cosmological redshift. More distant, older objects have a correspondingly larger redshift, leading astronomers to often use redshift and age interchangeably. Hyperion’s redshift of 2.45 means that astronomers observed the proto-supercluster as it was 2.3 billion years after the Big Bang.

Located in the COSMOS field in the constellation of Sextans (The Sextant), astronomers identified Hyperion by analyzing the vast amount of data obtained from the VIMOS Ultra-deep Survey which provides a 3-D map of the distribution of over 10,000 galaxies in the distant universe.

The team found that Hyperion has a very complex structure, containing at least seven high-density regions connected by filaments of galaxies, and its size is comparable to nearby superclusters, though it has a very different structure.

Brian Lemaux is an astronomer from University of California, Davis and LAM, and a co-leader of the team behind this result. He said:

Superclusters closer to Earth tend to a much more concentrated distribution of mass with clear structural features. But in Hyperion, the mass is distributed much more uniformly in a series of connected blobs, populated by loose associations of galaxies.

This contrast, the astronomers say, is most likely due to the fact that nearby superclusters have had billions of years for gravity to gather matter together into denser regions — a process that has been acting for far less time in the much younger Hyperion.

Given its size so early in the history of the universe, astronomers expect Hyperion to evolve into something similar to the immense structures in the local universe such as the superclusters making up the Sloan Great Wall or the Virgo Supercluster that contains our own galaxy, the Milky Way.

Source: The progeny of a Cosmic Titan: a massive multi-component proto-supercluster in formation at z=2.45 in VUDS

Bottom line: A team of astronomers have identified a gigantic supercluster of galaxies forming in the early universe.


November 9, 2018

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