Astronomers were horrified: The most distant galaxy ever discovered, which comes from the distant ages of the universe 13.5 billion years ago, was described Friday in a study whose results have not yet been confirmed by further observations.
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It took more than 1,200 hours of sky observation, using four telescopes, to find “HD1,” an extremely bright object “its red color surprisingly consistent with the characteristics of a galaxy 13.5 billion years away,” explains its discoverer Yuichi Harikan, in A press release was published on the sidelines of the study by the Royal Astronomical Society.
A hunch that additional data, collected by the ALMA observatory in Chile, supported it: HD1 is located 100 million years from GN-z11, so far the record holder for the farthest galaxy.
Therefore, HD1 was born only 300 million years after the Big Bang, the period of the primordial universe. The light it emits has traveled for 13.5 billion years to reach Earth.
To determine its age, scientists measured the redshift of its original light. As the universe expands, the distance between objects expands. The further back in the past, the greater the distance between these objects and the greater the extension of their light, shifting towards increasingly red wavelengths.
“When I found this red, I had chills,” says an astrophysicist from the University of Tokyo, one of the authors of the study published in the Astrophysical Journal.
Black hole?
But there’s a catch: Scientists have also measured extremely strong intensity of ultraviolet radiation there, a sign of activity that theoretical models of galaxy formation have not taken into account.
The study authors then put forward two hypotheses: the young galaxy would have been an especially fertile ground for star formation, producing about 100 of them annually — at a rate ten times higher than expected.
These stars can be called “third clusters” that astronomers have not observed before. These first generations of stars were “more massive, brighter, and hotter than modern + stars,” according to Fabio Paccucci, of the Harvard Center for Astrophysics (US), lead author of the study, which is adapted from this study.
Another path: a supermassive black hole at the heart of the galaxy. Whoever swallows huge amounts of gas will emit strong ultraviolet radiation.
But for that, the black hole would have to be 100 million solar masses. “Reaching such a mass in such a short time is not very credible,” astrophysicist Françoise Coombs, of the Paris-PSL Observatory, who was not involved in the study, told AFP.
To remove the unknown, the HD1 galaxy was chosen as a target for the James Webb Space Telescope and its unparalleled ability to see the very distant universe.
