Astronomers have made a groundbreaking discovery by identifying the most distant pair of interacting supermassive black holes ever observed. This extraordinary duo, in the process of merging, existed when the universe was a mere 740 million years old. The light from this system, named ZS7, has traveled over 13 billion years to reach us, offering invaluable insights into the growth of supermassive black holes.
The ZS7 system is no lightweight. Each of these black holes is ten times heavier than Sagittarius A*, the supermassive black hole at the center of our Milky Way. One of the black holes has been directly measured to be 50 million times the mass of our Sun.
“The mass of the other black hole is likely similar, although it is much harder to measure because this second black hole is buried in dense gas,” stated Professor Roberto Maiolino from the Kavli Institute for Cosmology.
The discovery was made possible by the unparalleled capabilities of the James Webb Space Telescope (JWST). This infrared space telescope was able to track the unique signatures of supermassive black holes accreting matter, a feat unachievable by ground-based telescopes.
“We found evidence for very dense gas with fast motions near the black hole, as well as hot and highly ionized gas illuminated by the energetic radiation typically produced by black holes during their accretion phases,” explained Dr. Hannah Übler of Cambridge’s Cavendish Laboratory and the Kavli Institute for Cosmology.
These observations reveal the intricate details of ZS7, showcasing it as an interacting system destined to merge into a single, much larger black hole. This insight is crucial for understanding how some supermassive black holes achieve their colossal sizes, even at the dawn of the universe.
“Our findings suggest that merging is an important route through which black holes can rapidly grow, even at cosmic dawn,” Übler added.
Looking ahead, the future gravitational observatory LISA, scheduled for launch in the 2030s, will have the ability to measure the gravitational waves from such merging supermassive black holes, further advancing our understanding of these cosmic giants.
These groundbreaking results have been published in the journal Monthly Notices of the Royal Astronomical Society.
