An international team of astronomers has discovered the oldest black hole to date, as its existence dates back to an era when the universe was barely 400 million years old, according to a study whose results were published yesterday, Wednesday.
Jan Schulz, an astrophysicist at the Kavli Institute of Cosmology at the University of Cambridge, said that this discovery postpones the date of the oldest massive black hole by “about 200 million years.”
The co-author of the study published in the journal “Nature” pointed out that this study “will feed a new generation of theoretical models” to explain the existence of a similar phenomenon in the young universe, more than 13 billion years ago.
The mass of this black hole is estimated at 1.6 million times the mass of our sun. It is invisible, like all black holes, and absorbs the matter surrounding it by emitting an enormous amount of light in its surroundings.
It is this light that made it possible to discover the galaxy with the black hole at its heart, which was named “GN-Z11” when its discovery was announced in 2016 using the Hubble Space Telescope.
GN-Z11 was then the oldest galaxy observed by Hubble, and therefore the most distant, until the use of the James Webb Space Telescope began in 2022, which made it possible to discover the black hole in GN-Z11.
This discovery is in addition to other discoveries made available by the James Webb Telescope, which reveal a young universe that includes objects brighter than expected. The black hole discovered by the international team led by the University of Cambridge dates back to 430 million years after the Big Bang. It is the period of cosmic dawn, when the first stars and galaxies were born at the end of the so-called “dark” ages.
The problem for a black hole this size is understanding how it could grow so fast. It usually takes hundreds of millions or billions of years with those discovered later.
An astrophysicist at the Paris Institute of Astrophysics, Stephane Charlot, a participant in the study, explains to Agence France-Presse that its characteristics “indicate faster and earlier growth than the growth of other black holes known in ancient times.”
Therefore, “the mechanisms of black hole formation in the young universe could be different from those we know in the closer universe,” Charlo said.
If we stick to the classical scenarios, “the universe is too small to host such a massive black hole, so we have to think about other ways for it to appear,” says Roberto Maiolino, an astrophysicist at the University of Cambridge and the first author of the study, in statements reported by a statement.
Theorists imagine that such a “large” object was born 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 born, the GN-Z11 black hole may have devoured the surrounding gas to grow rapidly. All this is more easily done, because “observations seem to indicate a high density of this gas,” according to Charlo.
The study does not rule out any of these scenarios, according to Jan Schulz, who is counting on the unusual observational capabilities of the James Webb Telescope to shed light on this phenomenon.
“We can expect to discover other objects when we have a greater number of in-depth observations of larger parts of the sky,” says the astrophysicist.
(AFP)
