Wednesday, December 7

James Webb detects two of the first galaxies ever seen | Digital Trends Spanish

The James Webb Space Telescope has discovered two of the first galaxies ever seen in the universe, and they’re much brighter than expected, meaning astronomers are reconsidering their beliefs about how the first stars formed.

“These observations just make your head explode,” said Paola Santini, one of the researchers, in a release. “This is a whole new chapter in astronomy. It’s like an archaeological dig, when suddenly you find a lost city or something you didn’t know. It’s just amazing.”

two of the galaxies The most distant views to date are captured in these Webb images of the outer regions of the giant galaxy cluster Abell 2744. The galaxies are not within the cluster, but many billions of light-years behind it. NASA, ESA, CSA, T. Treu (UCLA)

The two galaxies are thought to be billions of years old, from just 100 million years after the Big Bang. Webb is able to look back at some of the earliest galaxies, because he operates in the infrared range, which means he can see galaxies that are redshifted.

Redshift occurs when light from a distant galaxy is shifted to the red end of the spectrum due to the expansion of the universe. The stronger the change, the more distant the galaxy. Light from some galaxies travels so far that it moves outside the visible light spectrum and into the infrared, where Webb can see it. Previous research had estimated that some galaxies detected by Webb could have a redshift as high as 14, but recent results are more precise thanks to better instrument calibration and suggest a redshift for the two galaxies of 10.5 and 12.5. , respectively.

Webb also takes advantage of a phenomenon called gravitational lensing, in which a massive object like a galaxy or cluster of galaxies is so massive that it warps space and acts like a magnifying glass, allowing researchers to see even more distant galaxies behind it.

The big surprise is that the two observed galaxies are much brighter than the researchers had thought they would be. They were also seen very quickly, in the early days of Webb’s observations, suggesting that early galaxies could be more numerous than previously thought.

“We have nailed something that is incredibly fascinating. These galaxies should have started joining perhaps only 100 million years after the Big Bang. No one expected that the dark ages would have ended so early,” said another of the researchers, Garth Illingworth. “The early Universe would have been only a hundredth of its current age. It is a time span in the evolving cosmos of 13.8 billion years.”

The researchers suggest that either early galaxies could be much more massive than previously thought, with many more stars than expected, or that they could be less massive but with stars that shone very brightly and are quite different from the stars that see today. To learn more and confirm the age of these universes, the researchers plan to make more observations with Webb’s spectroscopy instruments.

“Everything we see is new. Webb is showing us that there is a very rich universe beyond what we imagine,” said researcher Tommaso Treu. «Once again the universe has surprised us. These early galaxies are very unusual in many ways.”

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