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Evidence suggests that the 50m-solar-mass black hole predates its host galaxy.
Researchers using NASA’s James Webb Space Telescope have detected clear evidence that some supermassive black holes were enormous from the beginning, forming without a stellar collapse phase and without a significantly more massive host galaxy to feed them.
The research team observed images of Abell2744-QSO1 (QSO1), which is a prototypical ‘little red dot’ that existed some 700m years after the Big Bang. Little red dots were discovered by the James Webb Telescope and are the subject of significant research within the wider space exploration eco-system.
Using the Webb Telescope’s imaging and spectroscopic features, such as integral field unit and NIRspec (near infrared spectrograph) tech, the team of researchers mapped the motion and composition of gas orbiting a black hole in the centre of QSO1. What was discovered is that the gas has Keplerian motion, meaning it orbits a central point in the same way that the planets in our solar system orbit the Sun.
“This is important because it tells us that most of the mass of QSO1 is concentrated in the black hole at the centre,” said Cambridge graduate student Ignas Juodžbalis, who is a lead author on one of the studies. “If the mass were more distributed, as it would be if there were a lot of stars, the gas would not have this perfect Keplerian rotation.”
“This is a remarkable finding,” said Roberto Maiolino of Cambridge University, a co-author of the recently published studies. “It’s a paradigm shift, a total revisiting of the classical scenarios of how black holes form and grow.”
Using the laws of gravity that govern Keplerian motion, for the first time the team was able to use gas velocity measurements to calculate the black hole mass directly.
The research indicated that not only is the black hole massive in size – around 50m solar masses – but it also makes up at least two-thirds of QSO1’s total mass, thousands of times greater than in nearby galaxies, where supermassive black holes make up a small fraction of the host galaxy’s total mass.
“It seems that we have found a black hole that does not have a substantial host galaxy and that has predated stellar processes,” said Juodžbalis. “This is very exciting because it is evidence for primordial black holes or direct collapse black holes, which have been theorised but not confirmed.”
QSO1 is believed to be around 1,300 light-years across, but its light has been travelling for more than 13bn years and it is easier to study, NASA said, than most other little red dots primarily because it is gravitationally lensed by galaxy cluster Abell 2744, also known as Pandora’s Cluster. QSO1 is magnified and triply imaged, appearing in three different locations in the sky.
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