by Using the James Webb Space Telescope (JWST), astronomers have spotted a supermassive black hole at “cosmic dawn” that appears to be too massive. The confusion comes from the fact that this huge void doesn’t seem to have been feasting on much surrounding matter during that time – but, to reach its size, you’d expect it to have been ravenous when time began.
The supermassive black hole, which powers a quasar at the heart of the galaxy J1120+0641, was observed as it was when the universe was only about 5% of its current age. It also has a mass that is over a billion times that of the sun.
Although it is relatively easy to explain how densely, and therefore later, billions of solar masses have grown into supermassive black holes, the merging and feeding processes that facilitate such growth are expected to take like a billion years. That means finding such massive black holes that existed before the universe was 13.8 billion years old is a real dilemma.
Since it began operations in the summer of 2022, the JWST has been remarkably effective at spotting such challenging holes at the cosmic dawn.
One theory related to the early growth of these vacuums is that they were engaged in a feeding frenzy known as “ultra-efficient feeding.” However, JWST’s observations of the supermassive black hole in J1120+0641 did not reveal any particularly efficient feeding mechanism in its nearby material. This finding casts doubt on the growth mechanism of the superfast black hole that is fed extremely fast and means that scientists may know even less about the early evolution of the cosmos than they realized.
Related: How did supermassive black holes get so big so quickly right after the Big Bang?
“Overall, the new observations only add to the mystery: Early quasars were remarkably normal,” team leader and Max Planck Institute for Astronomy (MPIA) postdoctoral researcher Sarah Bosman said in a statement. “Regardless of the wavelengths we look at, quasars are almost the same in every era of the universe.”
Supermassive black holes regulate their own diets
Over the past 13.8 billion years of cosmic history, galaxies have increased in size by gaining mass by absorbing surrounding gas and dust, by cannibalizing smaller galaxies, or by merging with larger galaxies.
About 20 years ago, before the JWST and other telescopes began to find massively troubled black holes in the early universe, astronomers assumed that supermassive black holes in the hearts of galaxies grew gradually by the processes that caused galactic growth.
In fact, there are limits to how fast a black hole can grow – a limit these cosmic titans have to fix themselves.
Due to the conservation of angular momentum, matter cannot fall directly into a black hole. Instead, a flat cloud of material called an accretion disk forms around the black hole. In addition, the massive gravity of the central black hole causes powerful tidal forces that create turbulent conditions in the accretion disk, heating it and allowing it to emit light across the electromagnetic spectrum. These emissions are so bright that they often exceed the combined light of all stars in the surrounding galaxy. The regions where all this happens are called quasars, and they represent some of the brightest celestial objects.
This brightness also has another function. Despite not having mass, light exerts pressure. This means that the light emitted by a quasar exerts pressure on the surrounding matter. The faster the black hole is powering the quasar feeds, the greater the radiation pressure and the more likely the black hole will cut off its own food supply and stop growing. The point where black holes, or any other predator, starve by pushing away surrounding matter is called the “Eddington limit”.
That means supermassive black holes can’t feed and grow as fast as they want. Therefore, finding supermassive black holes with masses as high as 10 billion suns in the early cosmos, especially less than a billion years after the Big Bang, is a real problem.
Astronomers need to know more about early quasars to determine whether the early supermassive black holes were able to overcome the Eddington limit and become so-called “super-Eddington hunters”.
To do this, in January 2023, the JWST Mid-Infrared Instrument (MIRI) team focused on the quasar at the heart of J1120+0641, located 13 billion light-years away and seen as it was just 770 million years after the Big. Bang. The investigation is the first mid-infrared study of a cosmic dawn quasar.
The spectrum of light from this early supermassive black hole revealed the properties of the large ring-shaped “torus” of gas and dust that surrounds the accretion disk. This torus helps guide matter to the accretion disk, from where it is gradually fed into the supermassive black hole.
MIRI observations of this quasar have shown that the cosmic supply chain functions similarly to “modern” quasars that are closer to Earth and therefore exist in the later ages of the universe. That’s bad news for proponents of the theory that an enhanced feeding mechanism led to the rapid growth of early black holes.
Related Stories:
— 12 billion years of black hole history, revealed through X-rays and simulations
— At the heart of this distant galaxy are not 1, but 2 jet-bursting black holes
— Could Stephen Hawking’s famous theory finally be proven with these black hole ‘monsters’?
In addition, measurements of the region around the supermassive black hole, where the material was swirling at nearly the speed of light, were consistent with observations of the same regions of modern quasars.
JWST observations of this quasar revealed one major difference between it and its modern counterparts. The dust in the torus around the accretion disk had a temperature of about 2,060 degrees Fahrenheit (1,130 degrees Celsius), which is about 100 degrees hotter than the dust rings around supermassive black hole-driven quasars seen closer to Earth.
The research favors an alternative mode of early supermassive black hole growth that suggests these cosmic titans took precedence early in the universe, coming from the “seeds” of an already massive black hole. of the sun, forming directly through the collapse of early and massive gas clouds.
The team’s research was published on June 17 in the journal Nature Astronomy.
