Researchers uncover how galaxies and their black holes grew 12.9 billion light years ago

An international of researchers including the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI) have used the James Webb Space Telescope to uncover 12 black holes from 12.9 billion years ago, shedding light on how black holes and galaxies evolved in the early universe, reports a new study in Nature Astronomy.

Since the release of its first data in 2022, the James Webb Space Telescope (JWST) has made it possible for researchers to study extremely distant galaxies, reshaping our understanding of the formation and evolution of the first galaxies in the universe.

At the center of a galaxy is a supermassive blackhole weighing between a hundred-thousand to several hundred billion times the mass of the Sun. When a black hole shines brightly, it is called a quasar because it is emitting the energy of matter falling into the black hole. Quasars allow researchers to identify galaxies in the vast night sky, which they study to learn about how galaxies have evolved into the shapes and behavior we see today.

Observations of galaxies close to the Earth have shown a strong link between the mass of the galaxy and its central black hole, indicating that the two grow in tandem and influence each other over cosmic time—a process known as co-evolution. However, it is unclear how this relationship between the two, whose sizes differ by orders of magnitude, has been shaped. The only way to know for sure is to study galaxies far in the distant universe when the universe was young.

A team, led by Kavli IPMU Visiting Associate Scientist and Waseda University Waseda Institute for Advanced Study Lecturer Masafusa Onoue, who was a Kavli IPMU Project Researcher and Kavli IPMU-KIAA Kavli astrophysics fellow at the time of the study, Professor John Silverman, and Wuhan University Professor Xuheng Ding, and including the University of Tokyo School of Science, Ehime University, Ritsumeikan University, and the National Astronomical Observatory of Japan, studied quasars J2236+0032 and J1512+4422 using JWST’s Near Infrared Spectrograph (NIRSpec). These quasars had been discovered through the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), a wide-field imaging survey at the Subaru Telescope, and were among the targets followed up in JWST’s first year of science operations.

It turns out the parent galaxies had already grown to massive sizes, roughly 40-60 billion solar masses, hundreds of millions of years ago and were now in a phase where star formation activity was rapidly ceasing. Researchers say the change in properties could have been triggered by intense radiation emitted by the central black holes earlier. J2236+0032 and J1512+4422 are among the farthest known such galaxies.

Their results (Figure 1) took the researchers by surprise. 

“It was totally unexpected to find such mature galaxies in the Universe less than a billion years after the Big Bang. What is even more remarkable is that these ‘dying’ galaxies still host active supermassive black holes,” said Onoue.

Previous research had suggested that the activity of these massive black holes suppresses the growth of their host galaxies, accelerating their transition from star formation to quiescence. 

The team’s findings provide valuable evidence that the activity of supermassive black holes may have played a significant role in the evolutionary process of the earliest and fastest-growing galaxies in the early universe. This discovery captures that process in action, providing a new clue to understanding the complex growth history of galaxies and black holes in the early Universe. It is also a uniquely Japanese achievement, made possible by combining the Subaru Telescope’s powerful survey capability with JWST’s exceptional sensitivity.

Building on this discovery, the research team is continuing detailed analyses of the JWST data and planning future observations to further investigate the mysterious relationship between galaxies and black holes.

Details of this study were published in Nature Astronomy on August 11, 2025.