The first giant black holes grew at an ultra-fast rate thanks to the "help" of neighboring galaxies, whose radiation prevented stars from forming inside the "embryos" of future giants of the Universe, according to an article published in the journal Nature Astronomy.
“The collapse of a galaxy and the formation of a black hole with a mass of a million Suns occurs in this case in just 100 thousand years, an instant by cosmic standards. After a few million years, it grows to a mass of a billion Suns, which is noticeably faster than we expected to see,”said Zoltan Haiman of Columbia University in New York (USA).
It is believed that the centers of most massive galaxies are home to supermassive black holes, whose mass can range from a million to billions of times the mass of the Sun. The reasons for the formation of these objects are not yet entirely clear. Scientists initially believed that such objects arose in the same way as their "normal" cousins - as a result of the gravitational collapse of stars and the subsequent merger of several large black holes.
Observations of the first galaxies in the Universe made astrophysicists doubt this - it turned out that they were inhabited by black holes with a mass of tens of billions of Suns. Such objects, as calculations show, simply would not have time to grow to such a size if they were born small. Therefore, some scientists began to believe that supermassive black holes are born in more exotic scenarios - as a result of the collapse of giant clouds of "pure" atomic hydrogen or due to the presence of dark matter clumps in them.
Hyman and his colleagues have proposed another unusual scenario for the birth of the largest black holes in the Universe, in which the key role is played not by their "embryos", but by their space neighbors - other large galaxies.
The main obstacle to the growth of black holes, according to Hyman, are stars, or rather the process of their formation. When black holes begin to grow, clumps of matter, nebulae, where dozens and hundreds of stars are born, appear inside their "embryo". The stars will attract gas and prevent it from moving towards the black hole, due to which its growth actually stops by itself.
The process of star formation can be stopped if, at the moment when the "embryo" of a black hole is compressed, the hydrogen molecules in it will be split into individual atoms or ions. This, as Hyman and his colleagues suggested, could be accomplished by a fairly large galaxy with a significant number of young stars emitting large amounts of X-rays and ultraviolet radiation.
Scientists have tested this idea by creating a computer model of the early universe, inhabited by the first galaxies and the seeds of black holes. As their calculations showed, large galaxies can actually accelerate the growth of black holes in their "neighbors" if they are located at a certain distance from them and have the correct mass and brightness. Then the gas in neighboring galaxies breaks down into atoms, but does not heat up so much that the galaxy simply disintegrates into parts without forming a black hole.
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All these calculations, as scientists emphasize, do not exclude alternative scenarios for the formation of the largest black holes in the Universe. Hyman and his colleagues hope that the launch of the James Webb Telescope, the world's largest orbiting telescope, will help see these early galaxies and understand whether they really helped black holes grow or whether they were formed in some other way.