Astronomers have captured a long-sought cosmic phenomenon: a supermassive black hole’s disc and jet wobbling in real time as it consumes a star that wandered too close. By intensively monitoring the event over a year with a network of space- and ground-based telescopes, the team of astronomers detected a clear, synchronized motion of the disc and jet repeating roughly every 20 days. This is the first-ever observational evidence of disc-jet co-precession in a black hole system.
“When a star passes close to the supermassive black hole, the black hole’s strong gravity stretches it out and eventually tears it apart, so that material from the star starts falling onto it. Such an event becomes very bright; when a new one was discovered by an optical telescope, it triggered us to start observing the black hole in different wavelengths as quickly as possible”, says Santiago del Palacio, astronomer at Chalmers and part of the international research team.
This type of event in which a star approaches a supermassive black hole at the center of a galaxy and is torn apart by tidal forces is called a tidal disruption event, TDE. Some of the material from the star forms a hot accretion disk swirling around the black hole, releasing intense radiation, while some of the material is launched outward in thin, powerful and extremely fast jets. TDEs are therefore unique windows for studying the activation of quiescent black holes and the formation of relativistic jets.
The object of this study is located in the galaxy LEDA 145386, approximately 120 million light-years from Earth. In the case of the TDE called AT2020afhd, the star approached the black hole from an angle relative to its spin. Because the star’s debris falls in this same plane, the newly formed accretion disk becomes slightly tilted, and the dragging of spacetime caused by the black hole’s rotation makes the inner system wobble like a spinning top, with the emission from its accretion disk and jet rising and falling in unison. This phenomenon is known as Lense–Thirring precession, a long-standing prediction of Einstein’s theory of general relativity.
To fully observe an event like this requires several telescopes working at different wavelengths. The hot gas close to the black hole emits X-rays, revealing the accretion disk, while the jets produce radio waves further out. By combining these signals, the researchers could see the same rhythmic pattern in both regions.
After the initial observations were made in January 2024, the researchers quickly organized an international coordinated observation campaign, mobilizing multiple space- and ground-based telescopes for over a year of multi-wavelength monitoring.
“We had pre-approved observing time with X-ray telescopes already scheduled, but a lot of work was done on submitting prompt proposals to various observatories justifying the urgent need of nearly simultaneous radio observations”, says Santiago, who was active in the request and interpretation of the observational data.
Without the cooperation of many telescopes, the discovery would not have been possible. By coordinating observations so that different instruments looked at the source at roughly the same time, the team could verify that they all detected the same variations. This meant the data sets matched reliably and could be combined in the analysis, despite being collected with different facilities. The different radio observatories covered complementary epochs, ensuring that there was no gap in the monitoring.
“There is strong variability in this emission, with its intensity becoming up to four times brighter within a matter of days and then decaying in a similar magnitude. When you see something like this, the first question is “Is this real?”, because as scientists we always remain skeptical. But the careful analysis very convincingly showed that the radio and X-rays go up and down in phase, with a delay. This synchronized pattern is one of the clearest signs that the disk and jet were wobbling as a coordinated system over time, proving theoretical dictions”.
Santiago del Palacio concludes “Observational breakthroughs like this demand a lot of work, but it allows us to test models of black hole physics in ways that simply weren’t possible before.”
More information:
The study “Detection of disk-jet co-precession in a tidal disruption event” is presented in the publication Science Advances on 10 December 2025, by first author and leader of the study Yanan Wang, National Astronomical Observatories, Chinese Academy of Sciences, China, et al.
Space observations were conducted with the Swift, NICER, and XMM-Newton X-ray telescopes, while ground-based observations relied on the VLA, ATCA, e-MERLIN, and VLBA radio interferometers, complemented by optical data from China’s Xinglong 2.16 m and Lijiang 2.4 m telescopes, achieving full-wavelength coverage of the event.
For more information, read the press release: Astronomers Reveal a Co-Precessing Black Hole Disk-Jet System from National Astronomical Observatories, Chinese Academy of Sciences.
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