Observations of quasars reveal that many supermassive black holes were in place less than 700 million years after the Big Bang. However, the origin of the first black holes remains a mystery. Seeds of the first black holes are postulated to be either light (that is, 10-100 solar masses), remnants of the first stars, or heavy (up to 100,000 solar masses), originating from the direct collapse of gas clouds. Using data from NASA’s Chandra X-ray Observatory, astronomers have now detected an X-ray-luminous black hole in a gravitationally lensed galaxy identified by the NASA/ESACSA James Webb Space Telescope behind the galaxy cluster Abell 2744. Named UHZ-1, the black hole has a mass between 10 million and 100 million solar masses, and is 13.2 billion light-years away, which means the telescopes are peering back in time to when the Universe was only about 450 million years old. The discovery, reported in two papers in the journal Nature Astronomy and the Astrophysical Journal Letters, is consistent with a picture wherein black holes originated from heavy seeds.
Bogdán et al. and Goulding et al. combined data from Webb and Chandra to identify the growing black hole at the center of UHZ1. Image credit: NASA / CXC / SAO / Bogdán et al. / ESA / CSA / STScI / L. Frattare / K. Arcand.
“This is one of the most dramatic discoveries to come out of Webb and the discovery of the most distant growing supermassive black hole known. Indeed, it completely smashes the old record,” said Princeton University’s Professor Michael Strauss.
“We needed Webb to find this remarkably distant galaxy and Chandra to find its supermassive black hole,” added Dr. Akos Bogdan, an astronomer at the Harvard & Smithsonian’s Center for Astrophysics.
“We also took advantage of a cosmic magnifying glass that boosted the amount of light we detected. This magnifying effect is known as gravitational lensing.”
The astronomers found the early black hole in a galaxy named UHZ1 in the direction of the galaxy cluster Abell 2744, which is located 3.5 billion light-years from Earth.
The Webb data revealed UHZ1 is much more distant than the cluster, at 13.2 billion light-years from Earth, when the Universe was only 3% of its current age.
Then over two weeks of observations with Chandra showed the presence of intense, superheated, X-ray emitting gas in this galaxy — a trademark for a growing supermassive black hole.
The light from the galaxy and the X-rays from gas around its supermassive black hole are magnified by about a factor of four by intervening matter in Abell 2744, enhancing the infrared signal detected by Webb and allowing Chandra to detect the faint X-ray source.
The mass of the black hole is estimated to fall between 10 and 100 million solar masses, based on the brightness and energy of the X-rays.
This mass range is similar to that of all the stars in the galaxy where it lives, which is in stark contrast to black holes in the centers of galaxies in the nearby Universe that usually contain only about a tenth of a percent of the mass of their host galaxy’s stars.
“Now, finally discovering a black hole that was so large, when the universe was so young, tells us that the black hole must have been very large when it was initially formed, probably from the direct collapse of a massive gas cloud,” said Dr. Andy Goulding, an astronomer at Princeton University.
“It also means that astronomers can rule out other formation models, like the death of the first massive stars, because those couldn’t produce a black hole large enough to explain UHZ-1.”
“The black hole has only a very short time to grow. This means that either it grew extraordinarily fast or the black hole was simply born larger.”
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Á. Bogdán et al. Evidence for heavy-seed origin of early supermassive black holes from a z ≈ 10 X-ray quasar. Nat Astron, published online November 6, 2023; doi: 10.1038/s41550-023-02111-9
Andy D. Goulding et al. 2023. UNCOVER: The Growth of the First Massive Black Holes from JWST/NIRSpec – Spectroscopic Redshift Confirmation of an X-Ray Luminous AGN at z = 10.1. ApJL 955, L24; doi: 10.3847/2041-8213/acf7c5
