Nobody expected them. They weren’t supposed to be there. And now, no one can explain how they were formed.
Almost as massive galaxies as galaxies milky way And full of ripe, red stars appear to be dispersed in his deep-field images James Webb Space Telescope (Webb or JWST) During the early observation campaign, they are causing headaches for astronomers.
these galaxies, described in a new study based on Webb’s first data release, are so far away that they only appear as tiny red dots to the powerful telescope. By analyzing the light emitted by these galaxies, astronomers have established that they were observing them at the beginning of our universe, only 500,000 to 700,000 years after the great explosion.
These early galaxies are not surprising in themselves. Astronomers expected the first star clusters to appear soon after being moved from the so-called Dark Ages – the first 400,000 years of its existence when a thick haze of hydrogen atoms permeated space.
Related: 12 amazing discoveries made by the James Webb Space Telescope across the universe
But the galaxies in Webb’s images looked shockingly large, and stars Its very old. The new findings contradict current ideas about how the universe appeared and evolved in its early years, and don’t match previous observations made by Webb’s less powerful predecessor, Hubble Space Telescope.
“We had specific predictions for the type of galaxies that lived in the early universe: they are small and small,” Joel Lega, an assistant professor of astronomy and astrophysics at Penn State and one of the study’s authors, told SpaceX by email. “Previous studies of the early universe using Hubble and other instruments tended to find small, blue galaxies at early times: objects that formed recently from the primordial cosmic soup and were themselves building their own early stars and structures.”
Young stars generally shine bright blue. As they age, stars glow red as they burn through their fuel and cool. In the ancient galaxies that Webb was built to discover, astronomers weren’t expecting to see ancient red stars. Nor did they expect to find galaxies larger than perhaps a billion suns. But Liga said those red dots detected in Webb’s deep fields appear to be 50 times larger than that.
“The most massive galaxies in our sample are estimated to have masses [two to four times lower] Lega wrote about our galaxy, the Milky Way. “This was amazing – we found candidate galaxies as massive as our own when the universe was only 3% of its current age.”
Lega said that before astronomers can start rewriting theories of cosmology to explain how these galaxies came together so quickly after the Big Bang, they will have to make sure that the individual red dots they are looking at are not something else. Most of the alternative explanations also require entirely new concepts, Lega said.
“For example, stars in the early universe may emit light in strange ways due to their lack of heavy elements, and we may not be incorporating them into our models,” Lega wrote. Alternatively, perhaps our understanding of how stars form locally, for example how many stars form from gas as a function of star mass, is completely unworkable in the early universe. These things will also be exciting to discover and will also upend our understanding of star formation in the early universe – In a completely different way.”
The images that revealed these elusive galaxies were obtained by the Near Infrared Webcam (NIRCam) as part of the Cosmic Evolution Early Release Science (CEERS) program. Astronomers plan to soon turn Webb’s mirror back at these galaxies again, this time, to obtain spectra of light for those faraway points. Spectra divide the observed light according to its wavelength configuration thus revealing the chemical and physical properties of its source.
“The most important thing is that the spectra give very precise distances to these objects,” Lega said. The “distance” and “identity” of these objects are interdependent: if we know the distance, we can define the identity, and vice versa. So the spectrum will immediately tell us whether our hypotheses are correct. “
Just over six months after Webb’s team released an edition First notes From the Big Observatory, scientists are already challenged to rewrite their theories about the early universe.
“We looked at the very early universe for the first time and had no idea what we were going to find,” said Lega at the University of Pennsylvania. statement. (Opens in a new tab) “It turns out that we found something so unexpected that it actually creates problems for science. It calls into question the whole picture of early galaxy formation.”
the study Published in Nature on Wednesday (22 February).
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