An international team of astronomers has just discovered a quasar that is, to say the least… excessive. Called ID830, this object located at the edge of the primitive universe swallows matter at a dizzying speed – thirteen times higher than what current models estimate to be the “limiting speed” of growth of black holes. A discovery that revolutionizes our understanding of cosmic evolution, explains an article from Live Science.
ID830 is not a simple black hole: it is a quasar, that is to say a supermassive black hole, surrounded by a disk of incandescent gas and emitting intense jets of energy from its poles. The object radiates in several wavelengths, notably in X-rays and radio waves, a mixture which is however impossible if current theories are to be believed.
ID830 would date from a period when the universe was only 15% of its current age – around 12 billion years ago – and would already display a mass of 440 million suns, more than a hundred times that of the giant black hole at the center of the Milky Way, Sagittarius A*. An extraordinary cosmic glutton, therefore, which calls into question the way in which we thought that the first black holes could have grown after the Big Bang.
Black holes are usually constrained by a kind of “cosmic regime” called the Eddington limit, which sets the balance point between gravitational attraction and radiation pressure. When the black hole absorbs too much material, the radiation produced repels the surrounding gas, interrupting the accretion process and the material is released. But it happens, under certain extreme conditions, that a black hole manages to cross this threshold: we then speak of a super-Eddington regime, where matter collapses faster than it can be repelled.
How to explain this phenomenon
There are several theories: some researchers evoke particular geometric configurations, where matter flows at the equator while radiation escapes through the poles, avoiding hindering the fall of the gas. Others believe that these “binges” last only a few hundred years – a brief period on a cosmic scale.
Discoveries from the James Webb Space Telescope have already undermined the idea of slow growth of giant black holes. His observations show that many early quasars were already massive a few hundred million years after the Big Bang, defying all theoretical logic. To explain this rapid growth, some astrophysicists invoke Population III stars, the very first stars, gigantic and ephemeral, whose death would have given birth to “seeds” of already very heavy black holes.
But even these seeds are not enough to explain everything: to reach the masses observed, they would have to feed at the maximum rate for several hundred million years without interruption, a hypothesis difficult to reconcile with known physics.
An object that confuses all the cards
By analyzing ultraviolet light and X-rays emitted by ID830, the researchers calculated that it swallowed material thirteen times faster than the Eddington limit. Such a frenzy could be due to a violent event: the engulfment of a giant star or a massive cloud of gas. According to Japanese astronomer Sakiko Obuchi, this “growth crisis” would only last about three centuries, a blink on the scale of the universe.
What makes ID830 even more mysterious is that it combines radio emissions and x-rays, a mix that current models consider mutually exclusive. In theory, super-Eddington accretion should stifle radio activity – but here, both phenomena are occurring with unprecedented power. Researchers believe that this radiation comes from both polar jets and a billion-degree magnetic corona, a sort of cocoon of supercharged particles orbiting almost at the speed of light.
Beyond astrophysical curiosity, ID830 could help understand how the first galaxies formed. When a black hole grows this quickly, the energy it releases can heat and disperse surrounding gas, slowing the birth of new stars. In other words, these cosmic monsters were perhaps feeding at the expense of the galaxies that sheltered them.
Researchers also suspect that such hyperactive quasars were more numerous than previously thought in the early universe. If ID830 is not an exception but the rule, it will undoubtedly be necessary to rewrite a large part of the cosmology textbooks.
