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An artist’s depiction of Horeilana, a “galaxy bubble” that spans one billion light years.
Astronomers were the first to discover the “Galactic Bubble,” an almost unimaginably massive cosmic structure thought to be the fossilized remnants of the immediate aftermath of the Big Bang that resided in the galaxy’s backyard.
The bubble spans 1 billion light years and is 10,000 times wider than the Milky Way.
But this giant bubble, invisible to the naked eye, lies relatively 820 million light-years away from our home galaxy in what astronomers call the nearby universe.
Daniel Pommarede, an astrophysicist at the French Atomic Energy Commission, told AFP that the bubble could be “a spherical shell with a heart”.
Within its core lies the Boetus supercluster of galaxies, surrounded by a vast cavity sometimes called the Great Nothing.
This shell contains several other galactic superclusters already known to science, including the massive structure known as the Great Wall of China.
Pomarede said the bubble discovery was explained in a study he co-authored and published. astrophysical journal This week was “part of a very long scientific process”.
This confirms a phenomenon first described in 1970 by Jim Peebles, an American cosmologist and future Nobel laureate in physics.
He theorized that in the primitive universe (then a stew of hot plasma), the churning of gravity and radiation produced sound waves called baryonic acoustic oscillations (BAOs).
When sound waves ripple through the plasma, bubbles are created.
About 380,000 years after the Big Bang, this process stopped when the universe cooled and the bubble shape froze.
Then, like other fossilized remains after the Big Bang, the bubble grew larger as the universe expanded.
Astronomers previously detected BAO’s signal in 2005 when examining data from nearby galaxies.
But the researchers say the newly discovered bubble is the first known single baryon acoustic oscillation.
“Unexpected”
Astronomers called the bubble Horeilana (“sent a wakeful murmur”), taking its name from a Hawaiian creation chant.
The name comes from the study’s lead author, astronomer Brent Talley of the University of Hawaii.
This bubble was discovered by chance as part of Tully’s work searching for a new catalog of galaxies.
“That was unexpected,” Pomarade said.
In a statement, Tully said the bubble was “so huge that it overflowed to the edge of the empty sector we were analyzing.”
Pomarede said they worked with Australian cosmologist and BAO expert Karan Howlett to “mathematically determine the structure of the sphere that best corresponds to the data provided.” .
This allowed the trio to visualize Horeilana’s three-dimensional shape and the location of the Galactic Islands within it.
This may be a first, but many more bubbles may soon be discovered across the universe.
Europe’s Euclid Space Telescope, which launched in July, provides a broader view of the universe and could capture even more bubbles.
A giant radio telescope under construction in South Africa and Australia, called the Square Kilometer Array, could also provide new images of galaxies from a Southern Hemisphere perspective, Pomalede said.
For more information:
R. Brent Tully et al., Ho’oleilana: An Individual Baryon Acoustic Oscillation?, astrophysical journal (2023). DOI: 10.3847/1538-4357/aceaf3
R. Brent Tully et al., Cosmicflows-4, astrophysical journal (2023). DOI: 10.3847/1538-4357/ac94d8