“Our results also show that massive black holes have been shaping the evolution of galaxies from the very beginning.”
An international team of astronomers using the NASA/ESA/CSA James Webb Space Telescope has discovered the earliest known black hole merger. Long ago, in two galaxies far, far away, two colossal black holes collided when the Universe was just 740 million years old. This event, studied with the JWST, marks the most distant and earliest detection of a black hole merger ever recorded. This groundbreaking discovery sheds light on the formation and growth of black holes in the early Universe, providing valuable insights into their role in cosmic evolution during the Universe’s infancy.
These collisions are relatively common in more modern cosmic epochs, leading to the formation of increasingly massive black holes at galaxy centers. These supermassive black holes, containing millions to billions of solar masses, significantly influence the evolution of their galaxies. The system is known as ZS7.
Using JWST and the Hubble Space Telescope (HST), astronomers have discovered giant black holes appearing earlier in cosmic history, within the first billion years of the Universe. This discovery raises an intriguing question: how did these black holes become so massive so quickly? As black holes grow by accreting matter, the merging galaxies contribute to this matter-harvesting process, playing a crucial role in the growth of these supermassive black holes.
“Do they somehow get born big, or do they have to be built from initially smaller black holes that smash together to form the giants?” Andrew Pontzen, a cosmologist at University College London who did not contribute to the findings, says to the Guardian’s Hannah Devlin.
“This new evidence from [the Webb telescope] is indirect, but it helps suggest a major role for black hole collisions.”
One black hole is 50 million times more massive than our sun. The other is thought to be similar in size, but is buried in dense gas, which makes it harder to measure it, because it was blocked by dense gas.
“Our findings suggest that merging is an important route through which black holes can rapidly grow, even at cosmic dawn,” Hannah Übler, a researcher at the University of Cambridge in England, says in a statement from the European Space Agency. “Together with other Webb findings of active, massive black holes in the distant universe, our results also show that massive black holes have been shaping the evolution of galaxies from the very beginning.”
The team notes that once the two black holes merge, they will also generate gravitational waves. In the future, gravitational wave observatories, like the Laser Interferometer Space Antenna that is expected to launch to space in the mid-2030s, could allow scientists to measure the ripples in spacetime emanating from the merging of these two black holes and other mergers from long ago.
“Webb’s results are telling us that lighter systems detectable by LISA should be far more frequent than previously assumed,” Nora Luetzgendorf, LISA lead project scientist with the European Space Agency, says in the statement. “This is just the tip of the iceberg.”
These results have been published in the Monthly Notices of the Royal Astronomical Society.
