Foto: NASA GSFC.
NASA’s James Webb Space Telescope (JWST) has detected the most distant galaxies ever confirmed, which formed some 325 million years after the Big Bang. An international team of astronomers made spectroscopic observations and measured the redshift of several galaxies, which seemed extraordinarily distant, and obtained evidence for the first time that they are as distant as they seemed. They did this by comparing how red these galaxies appear to estimates of their actual colors, the scientists reported. In the first galaxy observations made by the JWST, the researchers could only approximate the redshift of each galaxy because they did not have detailed data on the spectra of the light coming from those galaxies, so many scientists viewed those findings with suspicion. skepticism due to lack of precise confirmation. Recently, after analyzing images captured by the JWST, a team of astronomers discovered two “exceptionally bright” galaxies that would have formed at the dawn of the universe. However, the authors themselves specified that the infrared estimates made with Webb must be confirmed with follow-up spectroscopic measurements. Now, JWST researchers from JWST’s Deep Advanced Extragalactic Survey (JADES) have confirmed the redshifts of four other extremely distant galaxies, ranging from around 10.4 to 13.2.
Undoubtedly the furthest The light from these galaxies has taken more than 13.4 billion years to reach us, as they formed between 325 million and 450 million years after the Big Bang, when the universe was only 2% of its current age. The previous record for the highest confirmed redshift was about 11, two of these galaxies have a redshift greater than 13. “It was crucial to show that these galaxies do in fact inhabit the early universe,” Emma Curtis-Lake of the University of Hertfordshire, UK, said in a NASA statement. “Seeing the spectrum revealed as we expected, confirming that these galaxies are at the true edge of our view, some farther than Hubble could see! It is a tremendously exciting accomplishment for the mission,” he concluded. Observations with the NIRSpec instrument took 28 hours over three days and covered 250 faint galaxies in total. Thanks to Webb’s exquisite sensitivity, they were able to make a precise measurement of the redshift of each galaxy and revealed the properties of the gas and stars in these galaxies. “These are by far the faintest infrared spectra ever taken,” said Stefano Carniani of Italy’s Scuola Normale Superiore. “For the first time, we have discovered galaxies only 350 million years after the Big Bang, and we can be absolutely sure of their fantastic distances,” said co-author Brant Robertson of the University of California Santa Cruz. As he explained, the formation of stars in these first galaxies would have begun about 100 million years before the age at which they were observed, so their first stars were created about 225 million years after the Big Bang.
Astronomer and co-author Sandro Tacchella from the University of Cambridge, UK, added: “It is difficult to understand galaxies without understanding the initial periods of their development.  So many questions about the galaxies have been waiting for Webb’s transformative opportunity, and we are delighted to be able to participate in revealing this story.” The results have been submitted for peer review and subsequent publication. The article that reports on the discovery of the distances is available online in this repository and the one that refers to the spectroscopic study of the stars of these galaxies can be consulted here.