An international team of astronomers has discovered the oldest black hole that actually existed at the dawn of the universe, when the universe was barely 400 million years old, according to a study published Wednesday.
Jan Schultz, an astrophysicist at the Kavli Institute of Cosmology at the University of Cambridge, told AFP that this discovery takes the discovery of the supermassive black hole back “about 200 million years.”
This co-author of the study published in the journal added, “It will feed a new generation of theoretical models” to explain such a phenomenon in the young universe more than 13 billion years ago. review nature.
We must imagine an object with a mass estimated at 1.6 million times the mass of our Sun. It is invisible, and like all black holes, it absorbs the matter surrounding it by emitting a huge amount of light in its surroundings.
It is this light that made it possible to discover the galaxy at its heart, called GN-z11, when its discovery was announced in 2016 using the Hubble Space Telescope.
GN-z11 was then the oldest, and thus most distant, galaxy observed by Hubble. Until the arrival of the James Webb Space Telescope in 2022, which made it possible to discover the black hole GN-z11.
This discovery adds to other discoveries made with James Webb, which reveal a young universe containing objects much brighter than expected.
The black hole discovered by the international team led by Cambridge dates back to 430 million years after the Big Bang. It is the time of cosmic dawn, when the first stars and galaxies are born at the end of the so-called “dark” ages.
Several scenarios
The problem for a black hole of this size is understanding how it could grow so quickly. It usually takes several hundred million or several billion years for those to be discovered later.
Its properties “suggest faster and earlier growth than other known black holes at very early times,” explains Stephane Charlot, an astrophysicist at the Paris Institute of Astrophysics and co-author of the study, to AFP.
He adds: Therefore, “the mechanisms of black hole formation in the young universe could be different from those we know in the closer universe.”
If we stick to classical scenarios, “the universe is too small to host such a massive black hole, so we have to think of other ways for it to appear,” says Professor Roberto Maiolino, a Cambridge astrophysicist and first author of the study. In a press release.
Theorists imagine that such a body was born “large” from the explosion of a massive star at the end of its life, or from the rapid concentration of a cloud of dense gas, without going through the stage of star formation.
Once well born, the GN-z11 black hole will devour the gas surrounding it to grow rapidly. All this more easily because “observations seem to indicate a high density of this gas,” according to Mr. Charlotte.
study nature “None of these scenarios are ruled out,” says Jan Schulz, who is relying on the unusual observing capabilities of the James Webb Telescope to shed light on the phenomenon.
“We can expect to discover other objects when we have a greater number of in-depth observations of larger parts of the sky,” the astrophysicist hopes.
