Using the NASA/ESA/CSA James Webb Space Telescope, an international team of astronomers found evidence for an ongoing merger of two galaxies and their massive black holes when the Universe was only 740 million years old. This indicates the most distant detection of a black hole merger ever obtained.
This is the first time such a phenomenon has been detected so early in the Universe. The system is known as ZS7.
Lead author Hannah Übler of the University of Cambridge in the United Kingdom said, “We found evidence for very dense gas with fast motions in the vicinity of the black hole, as well as hot and highly ionized gas illuminated by the energetic radiation typically produced by black holes in their accretion episodes. Thanks to the unprecedented sharpness of its imaging capabilities, Webb also allowed our team to separate the two black holes spatially.”
The mass of one of the two black holes is 50 million times greater than that of the Sun. Since the other black hole is hidden in dense gas, its mass is considerably more difficult to estimate, although it is probably similar.
The study suggests that merging is an important route through which black holes can rapidly grow, even at cosmic dawn. These findings further demonstrate that substantial black holes have shaped galaxy evolution since the beginning of time, in agreement with prior Webb discoveries of active, massive black holes in the distant Universe.
Additionally, according to the team, the two black holes will produce gravitational waves once they merge. The next generation of gravitational wave observatories, like the recently approved Laser Interferometer Space Antenna (LISA) mission by the European Space Agency, will be able to detect events like these. LISA will be the first space-based observatory dedicated to studying gravitational waves.
The observations used in the Galaxy Assembly with the NIRSpec Integral Field Spectroscopy program led to this discovery. Recently, the team was granted a new Large Programme in Webb’s Cycle 3 of observations, allowing them to thoroughly examine how giant black holes and their host galaxies interacted during the first billion years of the Universe.
This program will include a significant effort to find and characterize black hole mergers systematically. In addition to evaluating the function of merging in the early growth of black holes and the rate at which gravitational waves are produced from the beginning of time, this effort will measure the rate at which black hole merging happens at early cosmic epochs.
Journal Reference:
- Hannah Übler, Roberto Maiolino, Pablo G Pérez-González, Francesco D’Eugenio, Michele Perna, Mirko Curti, Santiago Arribas, Andrew Bunker, Stefano Carniani, Stéphane Charlot, Bruno Rodríguez Del Pino, William Baker, Torsten Böker, Giovanni Cresci, James Dunlop, Norman A Grogin, Gareth C Jones, Nimisha Kumari, Isabella La (2024). GA-NIFS: JWST discovers an offset AGN 740 million years after the big bang. Monthly Notices of the Royal Astronomical Society, 531 (1), 355-365. DOI: 10.1093/mnras/stae943