Open in full screen mode A black hole (Artistic illustration) Agence France-Presse An international team of astronomers has discovered the oldest black hole, which already existed at the cosmic dawn, when the Universe was just 400 million years old, according to a study published in the journal Nature (New window) (in English). 
The GN-z11 galaxy, shown in the box as it was 13 years ago .4 billion years, 400 million years after the big bang.
This detection sets back that of a massive black hole by around 200 million years, Jan Scholtz, astrophysicist at the Kavli Institute of Cosmology at the AFP, reported to AFP. ;University of Cambridge in the United Kingdom.
It will fuel a new generation of theoretical models to explain such a phenomenon in the young Universe, more than 13 billion years ago, added this co-author of the study.
We must imagine an object with an estimated mass of 1.6 million times that of our Sun. Invisible, like all black holes, it absorbs surrounding matter by emitting a phenomenal quantity of light at its periphery.
It is this light which made it possible to detect the galaxy at the heart of which it is lurking, called GN-z11 when its discovery was announced in 2016 using the Hubble space telescope. /p>Loading
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GN-z11 was then the oldest, and therefore most distant, galaxy observed by Hubble. Until the arrival in 2022 of the James Webb Space Telescope, which enabled the detection of the GN-z11 black hole.
This detection adds to others, carried out with James Webb, and which reveal a young Universe housing objects much more luminous than expected.
The black hole detected by the international team led by Cambridge dates back to 430 million years after the big bang. It is the time of the cosmic dawn, when at the end of the so-called dark ages the first stars and galaxies are born.
The problem, for a black hole of this size, is to understand how it could have grown so quickly. It normally takes times of several hundred million or several billion years for those discovered later.
Its characteristics suggest a faster and earlier growth than that of other black holes known at very ancient times, explains to AFP Stéphane Charlot, astrophysicist at the Institute of Astrophysics of Paris and co-author of the #x27;study.
And therefore, black hole formation mechanisms in the young Universe could be different from those we know in the closer Universe, he adds.
If we stick to classic scenarios, the Universe is then too young to host such a massive black hole, so we must consider other explanations for its appearance, observes Professor Roberto Maiolino, astrophysicist at Cambridge and first author of the study, cited in a press release.
Theorists imagine that such an object was born large, from the explosion of a supermassive star at the end of its life or from the rapid concentration of a dense gas cloud, without passing by the star formation phase.
Once well born, the black hole of GN-z11 would then have gorged itself on the surrounding gas to grow rapidly, all the more easily as observations seem to indicate a high density of this gas, according to Mr. Charlot.
L' The Nature study does not rule out any of these scenarios, according to Jan Scholtz, who is banking on the extraordinary observation capabilities of the James Webb telescope to shed light on the phenomenon. /p>
We can expect to detect others when we have a larger number of deeper and larger observations portions of the sky, hopes the astrophysicist.