Supermassive black holes seem to exist at the center of every galaxy, going all the way back to some of the earliest galaxies in the universe. And we don’t know how they got there. It shouldn’t be possible for them to grow from supernova remnants to supermassive sizes so quickly, and we don’t know of any other mechanism by which they could form that doesn’t require such extreme growth.
The existence of supermassive black holes in the early universe was already problematic, as it was thought impossible, but the James Webb Space Telescope has made things even worse by discovering an even older example of a galaxy with a supermassive black hole. In the latest example, researchers used the Webb telescope to reveal the characteristics of a quasar powered by a supermassive black hole that existed about 750 million years after the Big Bang. And it looks surprisingly ordinary.
Looking back
Quasars are the most luminous objects in the Universe, powered by the energetic energy of a supermassive black hole. They receive enough material from the surrounding galaxy to form a bright accretion disk and powerful jets, both of which emit large amounts of radiation. Quasars are often partially covered in dust, which allows them to glow by absorbing some of the energy emitted by the black hole. These quasars emit so much radiation that they eventually expel some of the nearby material from the galaxy entirely.
The presence of these features in the early universe therefore indicates that supermassive black holes not only existed in the early universe, but were also embedded in recent galaxies. But they have been very difficult to study. Firstly, we have not identified many quasars; there are only nine quasars that date back to when the universe was 800 million years old. Their distance makes them hard to resolve, and the redshift caused by the expansion of the universe stretches the intense ultraviolet light from many elements deep into the infrared.
But the Webb Telescope is sensitive to the infrared wavelengths where this radiation appears, and was specifically designed to detect objects in the early universe, so the new study is based on pointing the Webb Telescope at J1120+0641, the first of nine early quasars discovered.
And it looks… surprisingly normal — or at least a lot like quasars that have appeared in more recent times in the history of the universe.
Near normal
The researchers analyzed the continuum radiation emitted by the quasar and found clear signs that it is embedded in a hot, dusty doughnut-shaped ball of material, as seen in later quasars. This dust is slightly hotter than in more recent quasars, but this appears to be a general feature of these objects at this early stage in the history of the universe. Emission from an accretion disk is also evident in the radiation spectrum.
Various methods to estimate the mass production value of black holes in ten regions9 Its mass is many times that of the Sun, clearly putting it in the realm of supermassive black holes, and there’s evidence from a slight blueshift in some of its radiation that the quasar is blasting material away at speeds of around 350 kilometers per second.
There are a few oddities. One is that material appears to be falling inwards at about 300 kilometres per second. This could be because the material in the accretion disk is spinning away from us. But if this is the case, then the material spinning towards us on the other side of the disk should match up too. This has been observed several times in very early quasars, although the researchers admit that “the physical origin of this effect is unclear.”
One possible explanation they offer is that the quasar as a whole is on the move, having been jolted out of its position at the center of the galaxy by a previous merger with another supermassive black hole.
Another oddity is that there is also a very fast outflow of highly ionized carbon, moving roughly twice as fast as that of later epoch quasars, which has been observed before but is also unexplained.
How did this happen?
Despite its oddities, the object is very similar to modern quasars. “Our observations suggest that it is a torus of dust and [accretion disk] Can be settled in the surroundings [supermassive black hole] “Less than 760 million years since the Big Bang”
And this, too, is a bit problematic, because it points to the presence of a supermassive black hole that integrated into its host galaxy very early in the history of the universe. To grow to the size seen here, the black hole would push against something called the Eddington limit, which is the amount of matter a black hole can pull in, and beyond that limit, the radiation it produces would blow away nearby matter, cutting off the black hole’s food supply.
This suggests two possibilities. One is that these objects have been ingesting material far beyond the Eddington limit for most of their history, something we have never observed and certainly not the case for this quasar. The other possibility is that these objects were initially massive (about 10Four It would have a mass many times that of the Sun and would have fed itself at a more reasonable rate, but how something so large could form is unclear.
So the early universe is still a pretty mysterious place.
Nature Astronomy, 2024. DOI: 10.1038/s41550-024-02273-0 (About DOIs)