A distant galaxy in the newborn universe essentially resembles a full-grown adult when it should just look like a small child, new findings suggesting that galaxies can evolve much faster than previously thought.
Galaxies come in different shapes, colors and sizes. Much remains of a mystery as to how galaxies formed in the early Universe and how they evolved mature features such as rotating discs and central bulges of densely packed stars. To see this far back in time, astronomers must look at light from distant galaxies, but such targets are often too dim to see properly.
In the new study, the researchers focused on the galaxy ALESS 073.1. The starlight they detected from this galaxy came from 12.5 billion years ago, when “the universe was 1.2 billion years old, about 10% of its present age,” lead author Federico Lelli, an astrophysicist at Cardiff, said. University in Wales, at Space. com.
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Using the Atacama Large Millimeter / submillimeter Array (ALMA) in Chile, the scientists analyzed high-quality images they had successfully collected of the dust and gas from ALESS 073.1. They used this data to model how matter was concentrated in the galaxy and to calculate its movements.
Unexpectedly, the researchers discovered that the galaxy had both a rotating disk and a central bulge. They also found signs that it may even have the same kind of spiral arms as adult galaxies like the Milky Way extending from their cores.
“This galaxy looks like a grown adult, but it should just be a small child,” said Lelli.
The core of ALESS 073.1 also generated more energy than can be explained by stars. Previous work has suggested that such an “active galactic nucleus” (AGN) refers to the presence of a supermassive black hole that is millions to billions of times the mass of the sun.
Previously, researchers believed that central bulges formed slowly over time, due to gravitational instabilities in a galaxy or mergers between galaxies. “ALESS 073.1, instead, was able to form a large bubble in less than 1.2 billion years, making up about half of its stars,” said Lelli. “This young galaxy looks surprisingly mature.”
Previous research also suggested that galaxies that form in the native universe are generally expected to be chaotic, turbulent, and largely unstructured due to all the activity they go through, such as devouring gas from their surroundings and forming stars at very high speeds. . The orderly structure detected in ALESS 073.1 “goes against these expectations,” said Lelli.
These new findings suggest that galaxies can form mature features such as disks and bulges much faster and more efficiently than previously thought. “Structures such as bulges, regularly rotating disks and possibly spiral arms should form in less than a billion years, which is a challenge for current models of galaxy formation,” said Lelli.
In the future, the scientists want to collect similar, high-quality images for a dozen or so galaxies from the same cosmic era, Lelli said.
“These new observations will determine whether galaxies such as ALESS 073.1 are the rule or the exception in the primordial universe,” said Lelli. “The observations were supposed to take place last year, but unfortunately the ALMA observatory is closed due to the COVID-19 emergency.”
The scientists detailed their findings in the Feb. 12 issue of the journal Science.
Originally published on Space.com.