A galaxy gleaming in the Cosmic Dawn, just 300 million years after the Big Bang, has just been spotted harboring something it oughtn't.
JADES-GS-z14-0, new observations reveal, is rich with oxygen – which is an absolute banger of a surprise, since scientists had thought elements heavier than hydrogen and helium weren't around in significant quantities until much later in time.
It's yet another clue that the early Universe matured much more quickly than we thought possible.
"It is like finding an adolescent where you would only expect babies," says cosmologist Sander Schouws of Leiden Observatory in the Netherlands.
"The results show the galaxy has formed very rapidly and is also maturing rapidly, adding to a growing body of evidence that the formation of galaxies happens much faster than was expected."
The mere existence of JADES-GS-z14-0 was problematic enough for our cosmological models, since we believe that galaxies need quite a bit of time to grow. In order to be detectable to our telescopes across more than 13.4 billion light-years, the galaxy needed to be quite large and bright – too large and bright to be easily explained.
The other thing that takes time to grow is elements heavier than hydrogen and helium. When the Universe as we know it first winked into existence in the Big Bang, the first elements that formed were hydrogen and helium.
Overdensities in this medium led to the formation of the first stars. The gas collapsed in on itself under gravity; more gas fed the growth until the core was hot and dense enough to kickstart the fusion of hydrogen atoms into heavier and heavier elements.
It's only through this process of stellar core fusion that oxygen came to exist – and here's the sting in the tail. The star has to live its entire life and die in a supernova for those fused elements to disperse out into space.
That can happen in a relatively short timeframe; the lifetimes of the most massive stars can be less than 10 million years.
But when a team of astronomers took measurements of the galaxy using the powerful Atacama Large Millimeter/submillimeter Array in Chile, the amount of elements heavier than hydrogen and helium detected in JADES-GS-z14-0 was 10 times higher than predicted. The result suggests that the production rate is likewise beyond our wildest expectations.
"I was astonished by the unexpected results because they opened a new view on the first phases of galaxy evolution," says astrophysicist Stefano Carniani of the Scuola Normale Superiore in Italy.
"The evidence that a galaxy is already mature in the infant Universe raises questions about when and how galaxies formed."
Because space is expanding, the light emitted from distant galaxies has become stretched into red wavelengths due to the Doppler effect. JWST is the most powerful infrared space telescope ever built, optimized for detecting these redshifted objects.
Since it has launched, astronomers have discovered more large galaxies way earlier in the Universe than we expected to see, painting a very different picture of how the early Universe evolved in the first billion years after the Big Bang.
This latest discovery of oxygen in JADES-GS-z14-0 is just another piece of the puzzle, increasingly indicating that galaxies grew and evolved much more quickly than we thought in the early Universe.
Now we just have to figure out how that rapid growth changes the cosmological timeline, and what other assumptions we have about the early Universe need to be reexamined.
The research has been detailed in two papers accepted into The Astrophysical Journal and Astronomy & Astrophysics. They are available on arXiv, here and here.