The SSA22 Protocluster, also known as EQ J221734.0+001701, is a

galaxy protocluster A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-l ...

located at z=3.1 in the

SSA 22 The SSA22 Protocluster, also known as EQ J221734.0+001701, is a galaxy protocluster located at z=3.1 in the SSA 22 region. It is located at and was originally discovered in 1998.Astrophysical Journal, "A Large Structure of Galaxies at Redshif ...

region. It is located at and was originally discovered in 1998.Astrophysical Journal, "A Large Structure of Galaxies at Redshift Z approximately 3 and Its Cosmological Implications", Steidel, Charles C.; Adelberger, Kurt L.; Dickinson, Mark; Giavalisco, Mauro; Pettini, Max; Kellogg, Melinda, v.492, p.428, 01/1998, , In 2006, a multifilamentary structure measuring 200 million light-years in width was announced, coinciding with the protocluster. Discovered in 2005 by Ryosuke Yamauchi from Tohoku University in Sendai, Japan, and his colleagues, the structure was found in a region of the universe known to contain large concentrations of gas. The structure is a very distant object; the astronomers that discovered it were actually looking at something from 12 billion years ago. This object is made up of

lyman-break galaxies Lyman-break galaxies are star-forming galaxies at high redshift that are selected using the differing appearance of the galaxy in several imaging filters due to the position of the Lyman limit. The technique has primarily been used to select ga ...

and large gas bubbles, such as lyman-alpha blobs and lyman-alpha emitters gaseous filaments.Astrophysical Journal, "Large-Scale Filamentary Structure around the Protocluster at Redshift z = 3.1", Yuichi Matsuda et al., Volume 634, Issue 2, pp. L125-L128, , , Some of the gas bubbles that make up this colossal structure are up to 400,000 light-years across, over twice the diameter of the Andromeda Galaxy. Some scientists believe that these giant bubbles formed after massive stars born in the early universe exploded as supernovae and ejected their surrounding gases. The galaxies and gas bubbles that are part of this structure line up along three curved filaments, or arms, that formed approximately 2 billion years after the

Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the ...

. These filaments were observed with the help of the

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and Keck telescopes located on the Mauna Kea volcano in Hawaii. This structure is not only incredibly large, but also very dense; the galaxies located in each of the filaments are four times closer to each other than the universe's average. Before its discovery, astronomers had predicted the existence of a structure like this one. According to computer models, several of the most massive galaxies originated in structures like this. These galaxies are believed to have formed as a result of blobs like those constituent to this structure collapsing under their own gravity. Since the densest areas in the universe are thought to be the places where galaxies formed first, this structure may be one of the earliest to have formed. This structure may reveal when and how the first galaxies formed and could help us better understand how our own galaxy came to be.

References

{{Reflist Galaxy clusters