Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA), during which the ECU Southern Observatory (ESO) may be a partner, have revealed an especially distant and so very young galaxy that appears surprisingly like our Milky Way Galaxy. 

© ALMA (ESO/NAOJ/NRAO), Rizzo et al. | Most look-alike distant Milky Way sees by ALMA

The galaxy is thus far away its light has taken quite 12 billion years to achieve us: we see it because it was when the Universe was just 1.4 billion years old. it's also surprisingly unchaotic, contradicting theories that each one galaxy within the early Universe was turbulent and unstable. This unexpected discovery challenges our understanding of how galaxies form, giving new insights into the past of our Universe.

"This result represents a breakthrough within the field of galaxy formation, showing that the structures that we observe in nearby spiral galaxies and in our Milky Way Galaxy were already in situ 12 billion years ago," says Francesca Rizzo, a Ph.D. student from the Max Planck Institute for Astrophysics in Germany, who led the research published today in Nature. 

While the galaxy the astronomers studied, called SPT0418-47, doesn't appear to own spiral arms, it's a minimum of two features typical of our Milky Way: a rotating disc and a bulge, the big group of stars packed tightly around the galactic center. this is often the primary time a bulge has been seen this early within the history of the Universe, making SPT0418-47 the foremost distant Milky Way Galaxy look-alike.

"The big surprise was to search out that this galaxy is really quite just like nearby galaxies, contrary to any or all expectations from the models and former, less detailed, observations," says co-author Filippo Fraternali, from the Kapteyn Astronomical Institute, the University of Groningen within the Netherlands. within the early Universe, young galaxies were still within the process of forming, so researchers expected them to be chaotic and lacking the distinct structures typical of more mature galaxies just like the extragalactic nebula.

Studying distant galaxies like SPT0418-47 is prime to our understanding of how galaxies formed and evolved. This galaxy is to date away we see it when the Universe was just 10% of its current age because its light took 12 billion years to succeed in Earth. By studying it, we are going back to a time when these baby galaxies were just setting out to develop.

Because these galaxies are to this point away, detailed observations with even the foremost powerful telescopes are almost impossible because the galaxies appear small and faint. The team overcame this obstacle by employing a nearby galaxy as a strong magnifying glass an effect referred to as gravitational lensing allowing ALMA to determine into the distant past in unprecedented detail. during this effect, the gravitational pull from the nearby galaxy distorts and bends the sunshine from the distant galaxy, causing it to look misshapen and magnified.

The gravitationally lensed, the distant galaxy appears as a near-perfect ring of sunshine round the nearby galaxy, because of their almost exact alignment. The research team reconstructed the distant galaxy's true shape and also the motion of its gas from the ALMA data employing a new computer modeling technique. "When I first saw the reconstructed image of SPT0418-47 I couldn't believe it: a chest was opening," says Rizzo.

"What we found was quite puzzling; despite forming stars at a high rate, and so being the positioning of highly energetic processes, SPT0418-47 is that the most well-ordered galaxy disc ever observed within the early Universe," stated co-author Simona Vegetti, also from the physicist Institute for Astrophysics. "This result's quite unexpected and has important implications for a way we expect galaxies to evolve." 

The astronomers note, however, that although SPT0418-47 encompasses a disc and other features almost like those of spiral galaxies we see today, they expect it to evolve into a galaxy very different from the Milky Way System, and join the category of elliptical galaxies, another sort of galaxies that, alongside the spirals, inhabit the Universe today.

This unexpected discovery suggests the first Universe might not be as chaotic as once believed and raises many questions on how a well-ordered galaxy could have formed so soon after the massive Bang. 

This ALMA finding follows the sooner discovery announced in May of a large rotating disc seen at the same distance. SPT0418-47 is seen in finer detail, because of the lensing effect, and encompasses a bulge additionally to a disc, making it even more just like our present-day galaxy than the one studied previously.

Future studies, including with ESO's Extremely Large Telescope, will seek to uncover how typical these 'baby' disc galaxies really are and whether or not they are commonly less chaotic than predicted, opening up new avenues for astronomers to get how galaxies evolved.

This article was originally published in ESO. 

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