Huge Cosmic Structures Already Existed When the Universe Was a Baby

[Judi Lynn]

By Rafi Letzter - Staff Writer 3 days ago Space



This image shows the region where the ancient galactic structure was found. The blue shading shows the area it covers. The red objects in the zoomed-in bits are the 12 galaxies.(Image: © NAOJ/Harikane et al.)

Astronomers have discovered the oldest cluster of galaxies ever seen, which dates to the early universe.

The discovery, which could help explain the shape of the modern cosmos, reveals 12 galaxies that existed in a clump 13 billion years ago — just about 700 million years after the Big Bang. We can see them now because they're so far away in the expanding universe (13 billion light-years) that their starlight is only now reaching Earth. One of the galaxies, a mammoth named Himiko after a mythological Japanese queen, was discovered a decade ago by the same team.

Surprisingly, the other 11 galaxies aren't clustered around the giant Himiko, the researchers wrote in a paper that will be published on Sept. 30 in The Astrophysical Journal and is available as a draft on the website arXiv. Instead, Himiko sits at the edge of the system, which the researchers call a "protocluster" because it's so small and ancient compared to most of the clusters we can see in the universe..

"It is reasonable to find a protocluster near a massive object, such as Himiko. However, we're surprised to see that Himiko was located not in the center of the protocluster but on the edge, 500 million light-years away from the center," Masami Ouchi, a co-author of the paper and an astronomer at the National Astronomical Observatory of Japan and the University of Tokyo, said in a statement.

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