The The discovery of a giant arc of galaxies would jeopardize one of the fundamental principles of cosmology. If the existence of the arc spanning more than 3 billion light-years proves true, it would overthrow cosmology as we know it.
An international group of scientists, including researchers from the University of Lancashire, the University of California, and the University of Louisville, have discovered an immense galactic structure. They named him Giant Arch, since it is a large-scale structure that covers a fifteenth part of the observable universe. In astronomical terms, this is immensely large.
If the arc turns out to be real (it is now > 4 sigma), it would put cosmology in check. One of the basic principles in cosmology is that, on a large scale, matter in the Universe is uniformly distributed no matter where you look. However, the bow puts this foundation in check.
“It would overthrow cosmology as we know it,” cosmologist Alexia Lopez said at a virtual meeting news conference for the American Astronomical Society. «Our standard model, to say the least, fails.»
Quasars as a tracking clue
They made the discovery by studying the light from about 40,000 quasars captured by the Sloan Digital Sky Survey, which is a space research project using images within the visible spectrum. Quasars, for their part, are the flashing nuclei of galaxies so distant that they can only be perceived as points of light. Astronomers are able to capture them thanks to the fact that during the journey of their light towards Earth, part of it is absorbed by atoms in and around the foreground galaxies. In other words, they leave a kind of specific signature in the light that is later captured by telescopes.
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The signature of the Giant Arc of galaxies is in the magnesium atoms that have lost an electron, in the halos of galaxies some 9.2 billion light-years away. The light from quasars absorbed by these atoms traces a symmetrical curve across dozens of galaxies. It surprises researchers because of its immense size, reaching 3 billion light years from the observable Universe. That is, one fifteenth of the entire universe we know.
Astronomers discovered what they say is a giant arc of galaxies (smiley curve in the middle of this image) using light from distant quasars (blue dots) to map where in the sky that light was absorbed by magnesium atoms. in the halos (dark spots) surrounding foreground galaxies. Credits: A. Lopez.
Very low probability of chance
However, when it comes to space research, you have to remain calm and wait for objectivity to reach the status of veracity. To make sure of what they found, López and his team calculated the probabilities that the galaxies lined up in a giant arc by chance. In all three cases, the results suggest that the structure is real, there is only 0.00003% probability that it is a coincidence.
The standard model of cosmology seems not to be consistent with the new findings on the matter. Scientists will have to face the great challenge of developing new models to continue navigating the history of the Universe.
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