Billions of light years from Earth, a baby galaxy that is surprisingly similar to our own is lurking, surprisingly calm and unassuming, scientists said in research published Wednesday. The scientists said the discovery has changed their understanding of how galaxies form.
The galaxy, called SPT0418-47, is located 12 billion light years from Earth, according to a study published in the journal Nature. Astronomers at the Max Planck Institute for Astrophysics (MPI) spotted the young galaxy using the Atacama Large Millimeter/submillimeter Array (ALMA), one of the world's most powerful telescopes.
Even the most powerful telescopes struggle to capture detailed observations of such distant galaxies. But using an effect called gravitational lensing, the team employed the help of the gravitational pull of a nearby galaxy to act as a magnifying glass, allowing ALMA to see "into the distant past in unprecedented detail."
The galaxy appears as a near-perfect ring of light — a so-called "Einstein Ring."
Because the galaxy is so far away, astronomers are viewing it as it was when the universe was just 1.4 billion years old. They said SPT0418-47 is "surprisingly unchaotic" — contradictory to prevailing theories that all young galaxies are "turbulent and unstable" compared to more mature galaxies like the Milky Way.
"What we found was quite puzzling; despite forming stars at a high rate, and therefore being the site of highly energetic processes, SPT0418-47 is the most well-ordered galaxy disc ever observed in the early Universe," co-author Simona Vegetti, from MPI, said in a press release Wednesday. "This result is quite unexpected and has important implications for how we think galaxies evolve."
SPT0418-47 does not appear to have spiral arms like the Milky Way. But both SPT0418-47 and our galaxy have rotating discs and bulges — large groups of tightly-packed stars around their centers.
"This result represents a breakthrough in the field of galaxy formation, showing that the structures that we observe in nearby spiral galaxies and in our Milky Way were already in place 12 billion years ago," said co-author Francesca Rizzo, a PhD student from MPI.
Researchers reconstructed the galaxy's actual shape and the motion of its gas from ALMA data using a new computer modeling technique. "When I first saw the reconstructed image of SPT0418-47 I could not believe it: a treasure chest was opening," Rizzo said.
This is the first time scientists have spotted a bulge so early on in the history of the universe, the release said — making SPT0418-47 the more distant "Milky Way look-alike."
"The big surprise was to find that this galaxy is actually quite similar to nearby galaxies, contrary to all expectations from the models and previous, less detailed, observations," said co-author Filippo Fraternali, from the Kapteyn Astronomical Institute, University of Groningen in the Netherlands.
Studying a baby galaxy that allows astronomers to view the universe when it was just 10% of its current age is key to understanding how galaxies form and evolve. It's unclear how a well-ordered galaxy could have formed so soon after the Big Bang, and indicates the early universe may be less chaotic than once believed.
While they hold several similarities, astronomers expect SPT0418-47 to evolve into a galaxy distinctly unique from the Milky Way. They anticipate it will eventually join the class of elliptical galaxies.
In the future, astronomers hope to discern just how common these baby disc galaxies are, and how chaotic they are, in order to further our understanding of the evolution of our own galaxy.
First published on August 13, 2020 / 7:08 PM
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