Astronomers using NASA James Webb Space Telescope (JWST) and the Chandra X-ray Observatory have discovered the oldest and most distant X-ray-spitting quasar in the known universe, and it appears to be powered by the “seed” of an ancient supermassive black hole.
Quasars are the bright hearts of active galaxies fueled by active supermassive black holes that cause the intruding material to emit intense thermal radiation. as they feed. Quasars can be so bright across the electromagnetic spectrum that they often exceeds the combined light of each star in the galaxy around them.
This primordial quasar, called UHZ1, was observed at high energy X-ray light was emitted when the universe was no more than 450 million years old and therefore traveled through space for about 13.7 billion years to reach us. As such, this quasar may be a black hole “seed” in the early universe, which helps reveal how supermassive black holes grew to enormous masses, millions or even billions of times that of the sun.
“It is exciting to be able to detect the presence of a supermassive black hole at the center of the galaxy just 450 million years after the Big Bang,” said a co-author of the study. Pryamvada NatarajanProfessor of Astronomy and Physics at Yale University, said the statement. “NASA’s Chandra Space Telescope has detected X-rays from this distant quasar that has a supermassive black hole at its center.”
Related to: James Webb Telescope Shows Universe May Have Far Fewer Active Black Holes Than We Thought
The discovery of UHZ1 is detailed in a journal article Astronomy of nature.
Understanding how supermassive black holes got so massive
Scientists hypothesize that supermassive black holes grew to such massive sizes by starting as black hole seeds in the early Universe and steadily growing, seeping through matter and merging with other black holes.
The question is how big were these seeds to begin with? One version of this theory suggests that the early universe was filled with “light seeds,” black holes created when massive stars ran out of fuel. nuclear fusion and exploded in supernova explosions, collapsing under their own gravity.
However, this explanation does not give supermassive black holes enough time to reach the masses of millions, let alone billions, of suns that early astronomers observed these giants in the infant universe.
One idea to give supermassive black holes a “head start” in this process is that if they start growing from “heavy seeds”. Between 2006 and 2007, Natarajan developed a model that suggests that supermassive black hole seeds can form in galaxies where star formation is suppressed.
These would be satellite galaxies near the galaxies in the early universe that gave birth to the first stars. This model suggests that large disks of gas and dust in these satellite galaxies may have collapsed directly into heavy black hole seeds, instead of the first born stars eventually collapsing into black holes millions or billions of years later. These heavy seed black hole satellite galaxies will then merge with nearby main star-forming galaxies.
In 2017, Natarajan and colleagues proposed that supermassive black hole seed galaxies should be observable in the early universe due to their unique properties. In particular, the central black hole in a heavy-black hole seed galaxy will outgrow the stars of that galaxy. This should be visible as X-ray quasars for the Chandra X-ray Observatory as well as the still-unlaunched JWST, which Natarajan proposed in 2017.
Finding a heavy black hole seed
Now, six years later, the team’s predictions are paying off with the discovery of this distant X-ray quasar. UHZ1 was identified under the leadership of the team Agos Bogdanan astrophysicist at the Harvard and Smithsonian Center for Astrophysics and Andy GouldingPrinceton astrophysicist who combined the latest data from the Chandra X-ray Observatory and JWST to look behind the galaxy Abel 2744.
“UHZ1 is the first candidate that matches all of our predicted properties for this transient class of supermassive black hole galaxies,” Natarajan said. “And now we’re seeing the first compelling evidence. It’s an exciting intersection of themes, a culmination of everything I’ve been working on.”
Goulding believes there are many galaxies with heavier seeds out there waiting to be discovered.
“UHZ1 may only be the tip of the iceberg,” he said. “JWST has opened a new window on the early universe. It will certainly help us find more UHZ1s and ultimately understand whether supermassive black holes were common.”
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