Webb Telescope Finds Three Feeding Black Holes in One Galaxy From Early Universe

Astronomers using the James Webb Space Telescope have found three actively feeding black holes inside a single galaxy that existed just 1.2 billion years after the Big Bang, according to researchers at the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching. The galaxy, known as J0148-4214, has a redshift of z=5.02, and its light has traveled roughly 12.5 billion years to reach Earth.

"This is the first evidence of three active black holes in a single galaxy in the distant Universe," said Hannah Übler, research group leader at MPE and lead author of the study.

Two of the black holes sit near the galaxy's center, separated by a projected distance of just 620 light-years. The third lies much farther out, about 5,500 light-years from the center. All three are accumulating matter that spirals toward them through surrounding disks of gas and other material.

The team identified the black holes by studying the light emitted by hydrogen gas. Near a black hole, strong gravity drives gas to extremely high speeds, leaving recognizable signatures in the light's spectrum. That lets astronomers detect black hole activity even when the objects cannot be seen directly. In the galaxy's center, the researchers found an unusually complicated hydrogen emission pattern, which they say is best explained by two closely spaced black holes rather than one.

To tell them apart, the scientists used a technique called spectro-astrometry, which tracks subtle shifts in the positions of spectral emissions across the galaxy. This allowed them to locate both central black holes even though the telescope could not resolve them as two separate points of light. The observations also revealed the third black hole in the outer region. The work relied on Webb's Near Infrared Spectrograph in its integral field spectroscopy mode, which shows how light and its spectral signatures vary across different parts of a galaxy. Without that spatial information, the researchers say, astronomers likely would have identified only one of the three.

The black holes differ widely in mass. According to the researchers' calculations, they weigh roughly 80 million, 600,000 and 2 million times the mass of the Sun. The largest is not the most aggressive feeder. Its smaller neighbor, at about 600,000 solar masses, is accumulating matter at a much higher rate, with an estimated feeding rate that exceeds the maximum predicted by basic models of black hole growth, known as the Eddington limit. This rapid growth may offer clues to how some black holes became enormous in the limited time available in the early universe.

"The JWST data allowed us not only to identify the three black holes, but also to estimate their masses, accretion rates, and the stellar mass of the galaxy," said Dr. Giovanni Mazzolari, second author and MPE researcher. "We find a total stellar mass of about 1.3 billion suns, and the black holes represent a significant fraction of that."

The two central black holes are expected to merge within the next few hundred million years. Astronomers believe galaxy collisions were common in the early universe, and as galaxies merged, their central black holes could have drawn together and combined into ever larger ones. "They suggest that black hole merging may be an additional, fast route for their rapid growth in the early Universe," said Roberto Maiolino, a professor at the University of Cambridge and co-author.

The third black hole remains a puzzle. The researchers say it could be the remnant of an earlier merger that was pushed outward by a gravitational recoil, a kick that can occur when merging black holes emit gravitational waves unevenly. Alternatively, it may be slowly moving toward the galaxy's center, where it could eventually interact with the other two.

Übler said the finding suggests early-universe processes were efficient at bringing massive black holes together, setting the stage for the merger events expected to be detected by future gravitational wave observatories.

The source material does not describe specific limitations, and it does not say whether the study has been peer reviewed. It does note that other distant galaxies may host multiple growing black holes that have so far gone undetected. Finding more such systems could help scientists reconstruct the history of black hole mergers and understand how the universe produced its most massive black holes so early.