A huge bubble of galaxies has been discovered 820 million light-years away, and it bears the name Hawaii: Maui Now.

The University of Hawaii-led discovery of a massive bubble 820 million light-years from Earth is believed to be a fossil-like remnant from the birth of the universe. Astronomer Brent Tully of the University of Hawaii’s Institute of Astronomy and his team unexpectedly discovered the bubble within a network of galaxies. The entity was named Hoʻoleilana, a term derived from Komolepo, a Hawaiian creation hymn evoking the origin of the structure.

New findings published in The Astrophysical Journal suggest that these massive structures, predicted by the Big Bang theory, are the result of three-dimensional ripples in the matter of the early universe, known as baryon acoustic oscillations.

“We weren’t looking for it. It’s so massive that it extends to the edges of the strip of sky we were analyzing,” Tully said in a UH press release. “As an enhancement of galaxy density, it is a much stronger feature than expected. The very large diameter of a billion light-years exceeds theoretical expectations. If its formation and evolution are consistent with theory, this BAO is closer than expected, implying a high value for the expansion rate of the universe.

Astronomers located the bubble using data from Cosmicflows-4, which is by far the largest compilation of precise distances to galaxies. Tully co-published the extraordinary catalog in the fall of 2022. His team of researchers believes this may be the first time astronomers have identified a single structure associated with a baryon acoustic oscillation. This discovery could help advance scientists’ knowledge of the effects of galaxy evolution.

Huge bubbles of matter

In the well-established Big Bang theory, for the first 400,000 years, the universe was a cauldron of hot plasma similar to the interior of the sun. Inside the plasma, electrons are separated from the atomic nuclei. During this period, regions of slightly higher density began to collapse under gravity, even as the intense radiation bath tried to push the material away. This conflict between gravity and radiation made the plasma oscillate or ripple and spread outward, according to the report.

The largest ripples in the early universe depended on how far a sound wave could travel. This distance was determined by the speed of sound in plasma, approximately 500 million light-years, and was fixed when the universe cooled and stopped being a plasma, leaving vast three-dimensional ripples. Over the ages, galaxies have formed at density peaks, into massive bubble-like structures. The distribution patterns of galaxies, if properly characterized, could reveal the characteristics of these ancient messengers.

“I am the group’s cartographer, and mapping Hollielana in three dimensions helps us understand its content and relationship with its surroundings,” said researcher Daniel Bomarede from CEA Paris-Saclay University in France. “It has been an amazing process to build this map and learn how Holliana’s giant crustal structure is composed of elements that have been identified in the past as some of the largest structures in the universe.”

The same team of researchers also identified the Laniākea Supercluster in 2014. This structure, which includes the Milky Way, is small in comparison. Stretching about 500 million light-years in diameter, Laniakia extends to the near edge of this much larger bubble.

Detection of a single acoustic baryon oscillation

Tully’s team discovered that Hoʻoleilana was noted in a 2016 paper as the most prominent of several shell-like structures seen in the Sloan Digital Sky Survey. However, previous work did not reveal the full extent of the structure, and this team did not conclude that they had found a baryon acoustic oscillation.

Using the Cosmicflows-4 catalog, researchers were able to view the entire spherical envelope of galaxies, determine their center, and show that there is a statistical enhancement in galaxy density in all directions from that center. Hoʻoleilana includes several well-known structures previously discovered by astronomers, such as the Harvard/Smithsonian Great Wall of China containing the Coma Cluster, the Hercules Cluster and the Sloan Great Wall. Boötes Supercluster is located in its centre. The historic Boötes Void, a huge empty spherical area, lies within Hoʻoleilana.

Implications for Ho’oleilana

Simulation tests have shown that the shell structure identified as Hoʻoleilana has less than a 1% probability of being a statistical accident. Hoʻoleilana has the characteristics of a theoretically expected baryonic acoustic oscillation, including the emergence of a rich supercluster at its center, yet it emerges stronger than expected. In detail, Holliana is slightly larger than expected from Standard Model cosmology and what has been found from previous pairwise statistical studies of galaxy separation. The size is consistent with observations of the universe’s local expansion rate and galactic outflows on large scales that also point to subtle problems with the Standard Model.

*Courtesy of the University of Hawaii