Paris. The James Webb Space Telescope located the most distant galaxy detected to date, created during the initial expansion of the Universe, just 320 million years after the Big Bang, according to studies published on Tuesday.
The further away the galaxies are, and therefore younger, the more difficult they are to detect, since their light signal is very poor.
The first results from the James Webb Telescope (JWST), which began operating in July 2022, identified numerous “candidate” galaxies in the infrared spectrum, a wavelength invisible to the human eye that allows us to go back much further in time.
The Webb telescope has powerful infrared observation capabilities, which combined with spectroscopy, which analyzes light from an object to determine its chemical elements, located “unambiguously” the existence of four galaxies.
All of them are located at the red end of the spectrum, that is, they are very far away, with an age ranging between 300 and 500 million years after the Big Bang (which occurred 13.8 billion years ago), according to two studies published in nature astronomy.
At that time, the Universe was only 2 percent of its current age, and it was going through what scientists call a period of reionization: after the period known as the “dark ages,” it became active again and began to produce a large amount of of stars.
The most distant galaxy located by the JWST, named JADES-GS-z13-0, formed “320 million years after the Big Bang” and its light is the most distant observed to date by astronomers, he explained to afp Stéphane Charlot of the Paris Institute of Astrophysics, one of the study’s authors.
“A Feat”
The space telescope also confirmed the existence of the galaxy GM-z11, some 450 million years after the Big Bang, and which had already been detected by the Hubble telescope.
The four observed galaxies are very low-massive – barely a hundred million solar masses, compared to 1.5 billion for the Milky Way.
Instead, these galaxies are “very active when it comes to forming stars, in proportion to their mass”, details this astrophysicist.
The formation of stars is taking place “at approximately the same rate as the Milky Way” a speed “surprising in that initial stage of the Universe”, comments the researcher.
These galaxies are otherwise “very metal poor”, a discovery that confirms the usual theories of cosmology: the closer to the origin of the Universe, the less time these stars had to form complex molecules.
This new contribution from the JWST is “a technological feat,” says Pieter van Dokkum, an astronomer at Yale University, in a commentary attached to the study.
“Every month” the telescope exceeds “the frontiers of exploration,” he explains.
In February, James Webb located a group of six galaxies 500 to 700 million years old after the Big Bang, apparently much more massive than expected. If the existence of these galaxies were confirmed by spectroscopy, that could call into question some of the theories about the formation of the universe.
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