Astronomers using the James Webb Space Telescope (JWST) have detected a supermassive black hole that appears incredibly massive at “cosmic dawn.” The confusion stems from the fact that this huge void did not appear to be fed by much of the material in the environment at the time; but to reach its enormous size, it can be expected to become greedy when time begins.
The feeding supermassive black hole powering a quasar at the heart of galaxy J1120+0641 was seen as it was when the universe was only around 5% of its current age. It also has a mass billions of times that of the Sun.
While it is relatively easy to explain how supermassive black holes grow closer to billions of solar masses and therefore more recently, the merger and feeding processes that facilitate this growth are expected to take up to a billion years. This means finding such supermassive black holes that existed before the 13.8 billion-year-old universe was a billion years old is a real dilemma.
Since becoming operational in the summer of 2022, JWST has proven particularly effective at detecting such elusive black holes at the cosmic dawn.
One theory surrounding the early development of these cavities is that they are in a feeding frenzy called “ultra-efficient feeding mode.” However, JWST’s observations of the supermassive black hole in J1120+0641 did not show a particularly effective feeding mechanism in material close to it. This finding casts doubt on the mechanism of extremely fast feeding supermassive black hole growth and suggests that scientists may know less about the early evolution of the universe than they thought.
Relating to: How did supermassive black holes grow so quickly right after the Big Bang?
“Overall, the new observations only add to the mystery: The first quasars were surprisingly normal,” team leader and postdoctoral researcher Sarah Bosman at the Max Planck Institute for Astronomy (MPIA) said in a statement. “No matter what wavelength we observe them at, quasars are nearly the same throughout the universe.”
Supermassive black holes control their own nutrition
Over the last 13.8 billion years of cosmic history, galaxies have grown in size, gaining mass by absorbing surrounding gas and dust, cannibalizing smaller galaxies, or merging with larger galaxies.
About 20 years ago, before JWST and other telescopes began finding troublesome supermassive black holes in the early universe, astronomers had assumed that supermassive black holes at the hearts of galaxies were slowly growing larger, consistent with the processes that lead to galactic growth.
There are actually limits to how fast a black hole can grow; The boundaries of these cosmic giants actually help define them.
Due to conservation of angular momentum, matter cannot fall directly into the black hole. Instead, a flattened cloud of material called an accretion disk forms around the black hole. Moreover, the enormous gravity of the central black hole gives rise to strong tidal forces that create turbulent conditions in the accretion disk, heating it and causing it to emit light across the electromagnetic spectrum. These emissions are so bright that they often dwarf the total light of every star 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. Light exerts pressure even though it has no mass. This means that the light emitted by quasars repels surrounding matter. The faster the black hole that powers quasars feeds, the higher the radiation pressure, and the more likely it is that the black hole will cut off its own food supply and stop growing. The point at which black holes, or any other accumulators, starve themselves by pushing out surrounding matter is called the “Eddington limit.”
This means that supermassive black holes cannot feed and grow as fast as they would like. Therefore, the presence of supermassive black holes with masses as large as 10 billion Suns in the early cosmos, especially less than a billion years after the Big Bang, is a real problem.
Astronomers need more information about early quasars to determine whether early supermassive black holes crossed the Eddington limit and became “super Eddington accumulators.”
To do this, in January 2023, the team focused JWST’s Mid-Infrared Instrument (MIRI) on the quasar at the heart of J1120+0641, which is 13 billion light-years away and appears to be just 770 million years from the Great Galaxy. Bang. The research constitutes the first mid-infrared study of a quasar existing at the cosmic dawn.
The spectrum of light from this early supermassive black hole revealed features of the large, ring-shaped “donut” of gas and dust surrounding the accretion disk. This torus helps direct matter to the accretion disk, where it gradually feeds matter into the supermassive black hole.
MIRI observations of this quasar showed that the cosmic supply chain operated similarly to that of “modern” quasars that were closer to Earth and thus existed in later periods of the universe. This is bad news for proponents of the theory that an advanced feeding mechanism led to the rapid growth of early black holes.
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Additionally, measurements of the region around the supermassive black hole where matter rotates at nearly the speed of light were consistent with observations of the same regions of modern quasars.
JWST observations of this quasar revealed a major difference between it and its modern counterparts. Dust in the torus around the accretion disk had a temperature of about 2,060 degrees Fahrenheit (1,130 degrees Celsius); This was about 100 degrees hotter than the dust rings around supermassive black hole-powered quasars seen closer to Earth.
The research supports another method of early supermassive black hole growth, which suggests that these cosmic giants had a head start in the early universe and formed from already massive black hole “seeds” – the Sun, which formed directly from the collapse of early, massive gas clouds.
The team’s research was published June 17 in the journal Nature Astronomy.