'Second' Milky Way found 12 billion light-years away
Our Milky Way galaxy has a bit of a look-alike in an unlikely place: the early universe.
Astronomers used ALMA, or the Atacama Large Millimetre/submillimetre Array of telescopes, based in Chile, to find the galaxy located more than 12 billion light-years away from our own. That means the light from this galaxy has travelled for more than 12 billion years to reach us, so we're seeing the galaxy as it appeared when the universe was only 1.4 billion years old.
The telescope's image of the galaxy and accompanying study published on Wednesday in the journal Nature.
During the tumultuous early years of the universe, galaxies were likely just as unstable as they formed, lacking the structure associated with older galaxies like the Milky Way.
But the image of this galaxy challenges that theory, and it could change how astronomers understand galaxy formation as well as the early days of the universe.
"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 Francesca Rizzo, study author and postdoctoral student at the Max Planck Institute for Astrophysics in Germany, in a statement.
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The galaxy, named SPT0418-47, has two hallmarks of our galaxy, including its rotating disk-like structure as well as the bulge, or large group of stars corralled around the galaxy's centre.
This bulge of stars has never been seen this far back in the history of the universe.
The research team reconstructed the distant galaxy's true shape, shown here, and the motion of its gas from the ALMA data using a new computer modelling technique.
"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 Filippo Fraternali in a statement, study co-author and professor of gas dynamics and evolution of galaxies at the Kapteyn Astronomical Institute of the University of Groningen in the Netherlands.
Studying this galaxy allows astronomers to essentially peer back in time to when the universe was 10 per cent of its current age.
Given the distance of this galaxy, the researchers used a technique called gravitational lensing while observing with ALMA.
This uses the gravity of nearby galaxies to magnify distant galaxies by bending their light.
Due to gravitational lensing, the image shows SPT0418-47 as a ring of light around another galaxy.
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Computer modelling helped the researchers to reconstruct the actual shape of the galaxy.
"When I first saw the reconstructed image of SPT0418-47 I could not believe it: a treasure chest was opening," Ms Rizzo said.