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Surprisingly mature galaxy in the infant universe suggests galaxies form faster than we thought.




In the newborn universe, a distant galaxy essentially resembles an adult while it should only appear like a small child, recent observations that indicate galaxies will grow much faster than previously believed.


Galaxies are available in a range of shapes, colors, and sizes. Much remains a puzzle about the origin of galaxies in the early universe and how mature characteristics such as spinning disks and central bulges of closely packed stars have formed. Astronomers need to look at light from distant galaxies to peek too far back in time, but those targets are always too faint to see clearly.



In the latest report, researchers have concentrated on the ALESS 073.1 galaxy. Study lead author Federico Lelli, an astrophysicist at Cardiff University in Wales, told Space.com that the starlight they observed from this galaxy came from 12.5 billion years ago, when "the universe was 1.2 billion years old, about 10 percent of its current age,"


Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the scientists analyzed high-quality photographs of the dust and gas of ALESS 073.1 that they successfully obtained. To simulate how the matter was concentrated in the galaxy and measure its movements, they used this data.


The researchers unexpectedly found the galaxy had both a spinning disk and a central bulge. They also noticed evidence that it might also have the same kind of spiral arms that mature galaxies have spread from their centers, such as the Milky Way.


The heart of ALESS 073.1 also created more energy than can be described by stars. Prior study has indicated that such an "active galactic nucleus" (AGN) indicates millions to billions of times the mass of the sun in the vicinity of a supermassive black hole.


Previously, researchers assumed that, due to gravitational instabilities within a galaxy, or mergers between galaxies, central bulges formed slowly over time. "ALESS 073.1, instead, was able to form a big bulge, making up about half of its stars, in less than 1.2 billion years," Lelli said. "This young galaxy appears surprisingly mature."


Earlier studies have indicated that, due to all the action they are experiencing, galaxies developing in the primordial universe are usually supposed to be unstable, volatile and mostly unstructured, such as devouring gas from their atmosphere and forming stars at extremely high speeds. "is at odds with these expectations," is at odds with these expectations.


These recent results indicate that galaxies can be both quicker and more effective in shaping mature features such as disks and bulges than commonly assumed. In less than one billion years, structures such as bulges, normal spinning disks, and probably spiral arms must form, which is a high order for current models of spiral arms, Lelli said.


Scientists hope to gather related high-quality images from the same galactic period for a dozen or so more galaxies in the future, Lelli said.


"These new observations will establish whether galaxies like ALESS 073.1 are the rule or the exception in the primordial universe," Lelli said. "The observations were supposed to take place last year, but unfortunately the ALMA observatory was shut down due to the COVID-19 emergency."


In the Feb. 12 edition of the journal Science, the scientists detailed their observations.




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