Use The James Webb Space Telescope (JWST), astronomers have seen for the first time the light of ancient stars shining around some of the largest, brightest and oldest black holes in the universe.
Quasars — galactic nuclei containing an active supermassive Black holes — are among the oldest things in the universe. As the dust and gas accelerate toward the quasar’s central black hole, the quasar emits such bright radiation—usually a thousand times brighter but the entire Milky Way — that astronomers can hardly observe the fainter light of stars in the quasar galaxy. This makes it difficult to study the shape and mass of the galaxy.
But for the first time, MIT researchers were able to detect this mix of signals and detect faint starlight from stars in galaxies around some of the oldest quasars in the universe. Their results, published on May 6 in Astrophysical Journalreveal that, relative to their host galaxies, these ancient supermassive black holes are about 100 times larger than their counterparts in the nearby universe.
These results were possible thanks to the superior sharpness and resolution of JWST. During more than 120 hours of telescope operation, the team observed six quasars, all estimated to be about 13 billion years old—some of the oldest objects in the universe.
“The quasar dwarfs its host galaxy by orders of magnitude,” lead author of the study Minghao Yuepostdoctoral fellow at MIT, said ua statement. “And previous images weren’t sharp enough to make out what the host galaxy looks like with all its stars.”
Related: The James Webb Telescope confirms that something is seriously wrong with our understanding of the universe
Using improved data from JWST, the team was able to untangle the signals in these ancient galaxies by modeling which light appeared to come from a point source (the quasar) and which appeared to come from a more diffuse source (the surrounding stars). With relative luminosity in hand, the team then estimated the masses of each quasar and its host galaxy.
They calculated that the average quasar-to-galaxy mass ratio is 1:10, compared to 1:1000 for younger supermassive black holes in the nearby universe. But the explanation for why these ancient black holes are so massive is not immediately apparent.
“One of the big questions is to understand how could these monstrous black holes grow so largeso fast,” Yue said.
A standard black hole is formed when a star runs out of fuel and undergoes a gravitational collapse, triggering a supernova. The resulting black hole then gradually consumes material over its lifetime, growing larger over time.
“These black holes are billions of times more massive than Sunat a time when the universe is still in its infancy,” co-author of the study Anna-Christina Eilers, assistant professor of physics at MIT, said in a statement. “Black holes in the early universe appear to grow faster than their host galaxies.”
According to the standard way of formation of black holes, these black holes simply should not have had enough time to become as large as they are, which raises the possibility of alternative methods of formation.
One proposed mechanism is “direct collapse.” In this model, instead of the star collapsing to form a black hole, a giant cloud of dust and gas collapses, completely bypassing the star’s stage. In theory, this could generate much larger black holes — known as direct collapse black holes — giving them an evolutionary beginning to become supermassive earlier than is normally possible, although this is still a theory, in 2023 astronomers announced the first candidate for a galaxy containing a direct collapsing black hole.
Although the origin of these unexpectedly large black holes is still unknown, this work gives scientists insight into the development of these galaxies and quasars in the early universe.