Giant structures in the distant universe are upending our understanding of how the universe evolved.
Astronomers have discovered a gigantic, nearly perfect ring of galaxies some 1.3 billion light-years in diameter in the light that takes 6.9 billion years to reach us. It does not match any known structure or formation mechanism.
As the structure is named, the Big Ring could mean that the Standard Model of cosmology needs to be revised.
The discovery was led by astronomer Alexia Lopez from the University of Central Lancashire. presented At the 243rd General Meeting of the American Astronomical Society.
This is the second large structure discovered by Lopez and his colleagues. The first one is called the Giant Ark and is actually located in the same part of the sky. at the same distance. When the discovery of this arc was announced in 2021, astronomers were baffled. The Big Ring only deepens the mystery.
“Neither of these two supermassive structures can be easily explained by our current understanding of the universe.” lopez says. “And its gigantic size, unique shape, and cosmological proximity must certainly be telling us something important. But what, exactly?”
The most direct relationship seems to be something called baryon acoustic oscillations (BAO). These are giant circular arrays of galaxies found throughout the universe. These are actually spheres, fossils of sound waves that propagated through the early universe and then became frozen when space diffused and acoustic waves could no longer travel.
Big Ring is not BAO. All BAOs have a fixed size of about 1 billion light years in diameter. And a thorough inspection of the Big Ring reveals that it resembles the shape of a corkscrew aligned to look like a ring.
This leaves us with completely unanswered questions. “What the hell is that?” And what does it mean for the cosmic principle that in every direction, a particular patch of space should look about the same as every other patch of space?
“If we look at the universe on a large scale, we would expect matter to be evenly distributed everywhere in the universe, so there should be no noticeable irregularities above a certain size.” Mr. Lopez explains:.
“Cosmologists have calculated the structure’s current theoretical size limit to be 1.2 billion light-years, but both of these structures are much larger, with the Giant Arc nearly three times larger and the Big Ring’s circumference It is comparable to the length of the Giant Arc.”
But size is only one issue. The other is what it means for cosmology, the study of the evolution of the universe. Although the current model is the one that best fits what we have observed to date, there are some features that are difficult to explain under that framework.
There are other models that have been proposed to address these features.One such model is Roger Penrose’s conformal periodic cosmologya ring structure is expected as the universe undergoes an endless Big Bang expansion cycle, but conformal periodic cosmology is noteworthy. a serious problem in itself.
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Another possibility is that the structure is a type of topological flaw in the fabric of spacetime known as a cosmic string. These are thought to be like proton-wide wrinkles that appeared in the early universe as spacetime stretched and then locked into place. Although not much physical evidence has been found for cosmic strings, the theoretical evidence is quite promising.
At this point, no one knows what Big Ring and Giant Arc mean. It’s possible that they’re just a fortuitous arrangement of galaxies circling the sky, but that seems pretty unlikely.
The best hope is that we will discover more such configurations of galaxies scattered throughout the universe, hidden in plain sight.
“Current cosmological theory did not suggest that a structure of this scale would be possible.” lopez says. “There is probably one very large structure in all the universe that we can observe. But the Big Ring and the Giant Arc are two giant structures that are cosmologically adjacent. This is very attractive.”
This study was presented at the 243rd Congress. American Astronomical Society.