January 12, 2024

2024-01-12 16:13:41

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The discovery of the Great Ring, a gigantic cosmic object — spanning more than a billion light years — that appears linked to the Giant Arc (an equally extraordinary cosmic structure previously discovered), calls into question our current knowledge of the Universe. The sizes of these two objects exceed theoretical limits.

University of Central Lancashire doctoral student Alexia Lopez’s recent discovery of a cosmic structure of unprecedented scale was presented at the 243rd meeting of the American Astronomical Society. Also involving researchers from the University of Louisville and the University of Warwick, this revelation highlights the existence of the Great Ring, a spiral-shaped structure with a diameter of 1.3 billion light years .

Alongside the Giant Arc, another massive structure previously highlighted, the ring challenges the established theoretical limits of cosmology. These discoveries suggest a potential revision of our cosmological models.

An invitation to dream, ready to be worn.

The big ring: unexpected gigantism

The Great Ring presents characteristics that are difficult to imagine. With a diameter of 1.3 billion light years, this structure far exceeds the theoretical limits on the size of established cosmic structures. Its apparent size (from Earth) in the sky is regarding 15 times that of the Moon.

The researchers discovered this new structure by examining Magnesium-II (MgII) absorption lines in quasar spectra from the Sloan Digital Sky Survey (SDSS). Quasars are super-luminous and very distant galaxies. They act like gigantic lamps, illuminating much fainter intervening galaxies that would otherwise remain invisible.

The Great Ring is centered near 0 on the x-axis, extending approximately -650 to +650 on the x-axis (equivalent to 1.3 billion light years). © UCLan

Located near the Boötes constellation, it stands out not only for its gigantic size, but also for its position in the universe, which defies the assumption of cosmic homogeneity. According to this hypothesis, on a large scale, the universe should appear uniform and isotropic, with no distinctive structure on this scale.

In addition, the very nature of the Great Ring intrigues astronomers. Unlike a simple circular structure, as its name might suggest, it takes the form of a complex spiral, an alignment making it visible (frontally) from Earth. This spiral, propeller-like configuration is a rare feature. In fact, scientists are wondering regarding the forces and conditions that might have led to the creation of such a spiral structure on such a massive scale.

The giant arc: an intriguing neighbor

The Giant Arc, spanning 3.3 billion light years, is another anomaly that defies the theoretical limits of cosmology. Its size far exceeds the theoretical limit of 1.2 billion light years, which was previously considered the maximum size for cosmic structures.

Artist’s impression of the Great Ring (shown in blue) and the Giant Arch (shown in red) in the night sky. © Stellarium

This discovery, in conjunction with that of the Great Ring, poses a double challenge to theorists. It might force them to reconsider current cosmological models, particularly those concerning the formation and evolution of large-scale structures in the universe.

Furthermore, a relationship between these two astronomical phenomena might exist. Alexia Lopez explains in a communiqué : « The Great Ring and the Giant Arc are the same distance from us, meaning they existed at the same cosmic epoch, when the universe was only half its current age “. She adds : ”
They are also in the same region of the sky, just 12 degrees apart when looking at the night sky. Identification of two extraordinary ultra-large structures in such a close configuration raises the possibility that together they form an even more extraordinary cosmological system ».

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A real need for new theories

One of the hypotheses put forward by researchers to explain the formation of the Great Ring concerns baryonic acoustic oscillations (BAO). These oscillations originate from the first moments of the universe, resulting from density fluctuations in the primordial plasma. Today, they should appear, at least statistically, as spherical shells in the distribution of galaxies.

However, detailed analysis of the Great Ring revealed that it is not really compatible with the BAO explanation: the Great Ring is too large and is not spherical. This incompatibility suggests that the Great Ring might be the result of processes or phenomena still unknown or poorly understood within the current framework of cosmology.

Other explanations may be needed, some of which deviate from standard understanding in cosmology, such as conformal cyclic cosmology (CCC). According to this theory, rings in the universe might be a sign of the CCC. This theory suggests that the universe goes through successive cycles of expansion and contraction, and that some observed phenomena, such as the Great Ring, might be remnants of previous cosmic cycles.

An alternative explanation for the formation of the Great Ring might lie in the impact of cosmic strings. These structures, seen as long filaments or large-scale “topological defects”, might have formed during the early stages of the universe. Jim Peebles, Nobel Prize winner in physics in 2019, recently proposed the idea that cosmic strings might influence the genesis of certain features observed in the distribution of large-scale galaxies. This theory suggests that these strings, as they pass through space, might leave distinctive traces that manifest in the current structure of the universe.

Source : UCLan

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