The James Webb Space Telescope was the first peek into the distant universe to detect galaxies that appear too large to exist.
Six galaxies that appear to have formed in the first 700 million years of the universe have up to 100 times more mass than standard cosmological theory predicts, astronomer Ivo Labbé and colleagues report on February 22. nature. “Adding stars to these galaxies would be the highest mass available in the universe at that time,” says Labbé, of Swinburne University of Technology in Melbourne, Australia. “That’s how you know there’s something about your feet.”
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The telescope, also called JWST, released its first glimpse of the early cosmos in July 2022.SN: 7/11/22). Within days, Labbé and his colleagues spotted about a dozen objects that looked especially bright and red, a sign that they could be huge and far away.
“They exist immediately, as soon as you look at these images,” says astrophysicist Erica Nelson of the University of Colorado Boulder.
By measuring how much light each object emits at various wavelengths, they can give astronomers an idea of how long each galaxy is, and how many stars will need to emit all that light. The six objects that Nelson, Labbé and colleagues identified as having similar light came from no later than about 700 million years after the Big Bang. Those galaxies appear to hold up to 10 billion times the mass of our sun in their stars. One of them would contain the mass of a hundred billion suns.
“There was no time to do things that have as many stars as the Milky Way,” Nelson says. Our galaxy contains an estimated 60 billion stars alone — and it has had more than 13 billion years to grow into it. “It’s just crazy these things seem to be.”
In the standard theories of cosmology, the matter in the universe is confined slowly, small structures gradually coalesce to form larger ones. “If all these large galaxies are in the early ages, they’re not happening this way,” Nelson says.
One explanation may be that there is another, unknown way of forming galaxies, says Labbé. “It seems like the reservoir is that fast track, and the fast track breeds monsters.”
However, it is possible that some of these galaxies host supermassive black holes in their cores, says astronomer Emma Curtis-Lake of the University of Hertfordshire in England, who was not part of the new study. These apparitions could shine like stars instead of light from the steam and dust of the black cavern they devour. JWST is already a candidate for a supermassive black hole active in the history of the universe earlier than these galaxies, he says, so it seems not impossible.
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Finding so many supermassive black holes at such an early age would also be difficult to explain.SN: 3/16/18). But it would not require rewriting the standard model of cosmology as to how extra-massive galaxies might be.
“The formation and growth of black holes at these early times is not well understood,” he said. “There’s no tension there with cosmology, just new physics to understand how they can form and grow, and we didn’t have data like that before.”
To know for sure what these distant objects are, says Curtis-Lake, astronomers need to confirm the galaxies’ distances and masses using spectra, more precise measurements of galaxy light at multiple wavelengths (SN: 12/16/22).
JWST has already taken spectra of a few of these galaxies, and more are to come, says Labbé. “With luck, we’ll know more in a year.”
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