Astronomers using the James Webb Space Telescope have discovered a distant galaxy hosting three massive black holes. Located more than 12.5 billion light-years away, the system provides rare insight into how galaxies and their central black holes grew rapidly in the early universe.
Black holes typically grow by consuming surrounding gas or by colliding and merging with other black holes. While gas accretion remains the primary engine for most cosmic growth, a team of international astronomers has uncovered evidence that galaxy mergers played an outsized role during the early history of the universe.
Uncovering the Distant Triple System in Galaxy J0148-4214
The discovery centers on the galaxy cataloged as J0148-4214, situated at a redshift of z = 5.02. Because of this immense distance, light from the galaxy has traveled for 12.5 billion years to reach Earth, allowing researchers to observe it as it existed roughly 1.2 to 1.3 billion years after the Big Bang.
The James Webb Space Telescope could not image the individual black holes directly due to the extreme distance. Instead, researchers relied on the Integrated Field Spectroscopy unit on the telescope’s Near Infrared Spectrometer, known as NIRSpec-IFS. By analyzing the spectral fingerprints of hydrogen gas swirling at high velocities in the accretion disks around the black holes, the team detected multiple broad hydrogen emission regions.
“This is the first evidence of three active black holes in a single galaxy in the distant Universe.”
Hannah Übler, research group leader at the Max Planck Institute for Extraterrestrial Physics and lead author of the study
To separate the closely packed signals in the galactic core, the team applied spectroastrometry, a technique that monitors small spatial shifts in light across the galaxy. This method revealed that two of the black holes sit side by side in the center, separated by a projected distance of only 620 light-years. A third black hole was identified in the outer region of the galaxy, approximately 5,500 light-years away from the core.
Masses, Accretion Rates, and the Eddington Limit
Data gathered by the instrument allowed researchers to calculate the masses of the three black holes as well as the total stellar mass of their host galaxy. The findings reveal a total stellar mass of about 1.3 billion suns, with the black holes representing a significant fraction of that total.
The most massive black hole in the galactic center weighs in at approximately 80 million solar masses. Its immediate companion is much smaller, carrying a mass of about 600,000 solar masses, while the third off-center black hole possesses a mass of roughly 2 million solar masses.
Despite its diminutive size compared to the central giant, the 600,000-solar-mass black hole is feeding at an extraordinary pace, exceeding the Eddington limit. This theoretical ceiling governs the maximum rate at which material can fall toward a black hole before intense radiation from the heated accretion disk blows surrounding gas back outward.
“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.”
Dr. Giovanni Mazzolari, researcher at the Max Planck Institute for Extraterrestrial Physics and second author of the study
Implications for Early Universe Growth and Gravitational Waves
Astronomers have long sought to explain how supermassive black holes attained such massive scales so quickly within the first billion years of cosmic history. The discovery of multiple active black holes packed into a region just 1.7 kiloparsecs across supports the theory that simultaneous galaxy and black hole mergers provided a fast track for mass accumulation.
Hannah Übler added that the system sets the stage for future gravitational-wave observatories.
What Lies Ahead for Gravitational Wave Astronomy
Mergers involving supermassive black holes produce gravitational waves.
To detect the signals emitted by those in galaxy J0148-4214, scientists look toward future space-based instrumentation.
