According to one researcher, REBELS-25 existed until 700 million years after the Big Bang. paper Published in Royal Astronomical Society Monthly Notices.
This image shows the galaxy REBELS-25, observed by ALMA, superimposed on infrared images of other stars and galaxies. This infrared image was taken by ESO's Visible Infrared Survey Telescope for Astronomy (VISTA). Image credits: ALMA / ESO / National Astronomical Observatory of Japan / NRAO / Roland others. / Dunlop others. / Cas / Kare.
The galaxies we see today are very different from the chaotic, clumpy galaxies that astronomers typically observed in the early universe.
These messy early galaxies merge with each other and evolve into smoother shapes at an incredibly slow pace.
Current theory suggests that it would take billions of years of evolution for galaxies to become as ordered as our Milky Way, a rotating disk with an orderly structure like spiral arms.
However, the detection of REBELS-25 casts doubt on that timescale.
“Our understanding of galaxy formation predicts that most early galaxies appear small and messy,” said Dr Jacqueline Hodge, an astronomer at Leiden University.
In their study, Dr. Hodge and colleagues found that REBELS-25 existed at redshift z = 7.3 (when the universe was only 700 million years old), making it the most distant object ever discovered. They discovered that it was a strongly rotating disk galaxy.
“Seeing galaxies so similar to our own Milky Way and with strong rotational dominance adds to our understanding of how galaxies in the early universe evolved into the ordered galaxies of today's universe. It raises questions,” says Lucy Roland, a PhD student at Leiden University. University.
REBELS-25 was detected by the authors using the Atacama Large Millimeter/Submillimeter Array (ALMA).
To precisely identify the galaxy's structure and motion, they conducted follow-up observations at higher resolution with ALMA, confirming its record-breaking nature.
Surprisingly, the data suggested more developed features similar to the Milky Way, such as an elongated central bar and spiral arms, but more observations are needed to confirm this. Probably.
“Finding further evidence of a more evolved structure would be an interesting discovery, as this would be the most distant galaxy in which such a structure has been observed to date,” Rowland said.
“These future observations from REBELS-25, along with other discoveries of early rotating galaxies, could change our understanding of early galaxy formation and the evolution of the universe as a whole.”
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Lucy E. Rowland others. REBELS-25: Dynamically cold disk galaxy discovered at z = 7.31. MNRASpublished online October 7, 2024. doi: 10.1093/mnras/stae2217
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