A group of astronomers has discovered the first “galactic bubble,” a massive structure dating back to the dawn of the universe, approximately 140,000 years ago, according to a study published in the Astrophysical Journal.
We must imagine it as a structure with a diameter of 1,000 million light-years, that is, 10,000 times larger than our galaxy.
It is located in what astronomers call the Near Universe, about 820 million light-years from the Milky Way, and it resembles a “spherical shell with a core,” as French researcher Daniel Pomarade, an astrophysicist and co-author of the study, explains to AFP. this week.
The heart of this shell is the Bouvier Supercluster of galaxies, surrounded by a large void and enveloped by other superclusters and filaments of galaxies, like Sloan’s Great Wall.
This discovery is part of a “very long scientific process,” according to Bomarede, because it confirms the validity of the phenomenon described by American cosmologist and Nobel Prize winner in physics in 1970, Jim Peebles.
The scientist explains that in the primitive universe, which then consisted of a plasma of particles and light, the processes involved produced sound waves. These vibrations will create a kind of bubble with material in the middle inside the plasma.
The process stopped 380,000 years after the Big Bang, causing the shape of these bubbles to “freeze.” Then it grows according to the expansion of the universe, like the “fossils” of those eras.
This phenomenon, called baryon acoustic oscillations (BAO), had indirect evidence of its existence in 2005, from statistical analyzes of galaxy catalogues.
Until the discovery of Ho’oleilana, a word from a Hawaiian creative song that means “mutterings of awakening.”
This term is associated with the first author of the study, Richard Brent Tully, an American scientist at the Honolulu Institute of Astronomy.
In 2014, Tully, together with Boumaredi, had already discovered the Laniakea supercluster, the “super-sky” in Hawaii, which contains about 100,000 galaxies, including our own Milky Way.
Hoolelana was discovered by chance, through Tully’s studies of new galaxy catalogues.
“It was something unexpected,” says Bommaredi, who has been studying the mapping of this region of the sky.
The two researchers then contacted the young Australian cosmologist Colan Howlett from the University of Brisbane.
This third author of the study, an expert in the BAO and in the analysis of large galaxy catalogs, “mathematically determined the spherical structure that best matches the data provided.”
This allowed us to visualize the shape of Hollyana in three dimensions and the location of the archipelagoes of galaxies that comprise it.
Pommarid points out that this work contributes to a major topic in cosmology, which is the value of the Hubble constant. This allows us to calculate the expansion levels of the universe, which sees how galaxies continue to move away from each other, and how a bubble like Holliana continues to grow.
Other bubble discoveries are just beginning, thanks to instruments like the European Euclid Space Telescope, launched in July, which will help understand the expansion of the universe. Or also the upcoming Large Radio Telescope from South Africa, SKA, “to observe the universe on the southern side of our galaxy,” says Bommaredi.