The black hole discovered lurking at the cosmic dawn is too big to easily explain. It lies at the center of a galaxy called J1120+0641, and has a mass of more than a billion suns.
There are even bigger black holes all around us today. The problem is when With J1120+0641 less than 770 million years after the Big Bang, it’s hard to know how the black hole had enough time to gain such a large mass.
We’ve known about the galaxy and its crowded black hole for more than a decade, and scientists have had ideas about how it might have appeared. Now, notes using James Webb I’ve disproved one of those notions. By all accounts, J1120+0641 appears “shockingly normal,” leaving open more exotic explanations for the black hole’s increased weight.
J1120+0641 has been discovered. Announced again in 2011For a few years it remained the most distant known quasar galaxy. It was a good few years, actually. As far as we knew, J1120+0641 was an oddball, and there was only one possible explanation for its size left on the table.
Quasar galaxies are galaxies that contain a central supermassive black hole that is feeding at an enormous rate. They are surrounded by a huge cloud of gas and dust, which they are devouring as fast as they can. Friction and gravity around the black hole heat up the material, causing it to shine brightly.
But the speed at which a black hole can feed is not unlimited. The maximum stable rate is determined by Eddington limitafter which the hot material shines so brightly that The radiation pressure will exceed the force of gravitypushing matter away and leaving nothing for the black hole to feed on.
Now, black holes can briefly enter Eddington superaccretion, hurtling through that limit and gulping down as much material as possible before the radiation pressure kicks in. This is one possible explanation for the black hole at the center of J1120+. 0641, and just as we find them in larger numbers, there are other large black holes lurking at the beginning of the universe.
To look for signs of Eddington superaccretion, astronomers needed data of sufficient resolution to perform a detailed analysis of the galaxy’s light, looking for signs of extreme processes. For that, we needed the James Webb Space Telescope, the most powerful space telescope ever built, optimized to peer into these distant regions of space and time.
The James Webb Space Telescope observed the galaxy in early 2023, and a team led by astronomer Sarah Boseman of the Max Planck Institute for Astronomy in Germany crunched the light it collected to catalog the properties of the material surrounding the black hole: a massive torus of dust on the galaxy. Outskirts, a glowing disk swirling around and feeding into the black hole.
This analysis reveals that the black hole is actually feeding very normally — and there is nothing in its accretion that looks dramatically different from other, more recent quasar galaxies.
One possible explanation for the existence of these supermassive black holes is that extra dust has led astronomers to overestimate their masses. However, there is no sign of extra dust either.
That means J1120+0641 is what it appears to be: a fairly ordinary, star-like galaxy with a black hole that isn’t devouring material at a very high rate. The black hole, and the way it feeds, were relatively mature by the time we observed it, within a few hundred million years of the Big Bang.
“Overall, the new observations add to the mystery: early quasars were shockingly normal.” Boseman says“No matter what wavelengths we observe, quasars are almost identical throughout all ages of the universe.”
This means that Eddington superaccretion is not the answer to the growth of bafflingly massive black holes at the dawn of time.
Another leading explanation is that black holes initially formed from very large “seeds.” Rather than a slow, gradual process from something the size of a star, this theory suggests that black holes formed from the collapse of clumps of matter or even very massive stars with masses hundreds of thousands of times the mass of the Sun, giving their growth a head start.
As we find more and more of these giant monsters hiding in the mists of the early universe, this idea seems less outlandish, and more like the best possible explanation we have for this mysterious era in the history of our universe.
The research was published in Nature astronomy.
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