It was formed in the early ages of the Universe, only 320 million years after the Big Bang. The most distant galaxy ever detected has been observed by the James-Webb Space Telescope, according to two studies published Tuesday, April 4 in Nature Astronomy.
The more the galaxies are distant, and therefore young, the more they are difficult to detect as their light signal is weak. The first surveys of the James-Webb Telescope (JWST), in service since July 2022, had identified many galaxies « candidates » in the infrared, a wavelength invisible to the human eye and whose observation allows us to go far back in time.
The powerful infrared vision of its NIRCam imager, combined with observations in spectroscopy which analyzes the light coming from an object to determine its chemical elements, confirmed ” without ambiguity “ the existence of four galaxies. All located towards the red end of the spectrum, therefore very distant.
Their age: between 300 and 500 million years approximately after the Big Bang (which occurred 13.8 billion years ago), detail these studies. The Universe was then only 2% of its current age, in its so-called reionization period: after a so-called dark ages period, it kind of reignited and began to produce a huge number of stars.
The most distant of the galaxies flushed out by the JWST, baptized JADES-GS-z13-0, would have formed “320 million years after the Big Bang”and its light is the most distant ever observed by astronomers, explained Stéphane Charlot, of the Institute of Astrophysics in Paris, one of the authors of the study.
“A technological tour de force”
The space telescope also confirmed the existence of the galaxy GN-z11, which it dated to 450 million years after the Big Bang, and whose presence the Hubble telescope had detected.
The four galaxies observed are very low in mass – around a hundred million solar masses, compared to, for example, 1,500 billion for the Milky Way. But these galaxies are “very active in star formation, proportional to their mass”details the astrophysicist.
The formation of stars would take place there at about the same rate as [dans] the Milky Way “a speed “surprising so early in the Universe”, comments this CNRS researcher. Another lesson, these galaxies are “very low in metals”a discovery consistent with the standard model of cosmology: the closer we get to the origins, the less the stars have had time to form these complex molecules.
The JWST observation is “a technological tour de force”, welcomes Pieter van Dokkum, astronomer at the American University Yale, in a comment attached to the study. The telescope pushes back “almost every month the frontiers of exploration”always going further into the Universe, he underlines.
The World Buying Guides
Robot vacuum cleaners
The best robot vacuums
Lire
Last February, the instrument developed by NASA observed a population of six galaxies between 500 and 700 million years after the Big Bang, which seem much more massive than expected. If the existence of these galaxies were confirmed by spectroscopy, it could call into question part of the theory on the formation of the Universe.