Scientists have observed a spinning black hole dragging and twisting spacetime around it, confirming a century-old prediction from general relativity. The phenomenon was detected during the destruction of a star by a supermassive black hole. This discovery provides new insights into black hole spins and jet formation.
In a groundbreaking observation, astronomers have witnessed the Lense-Thirring precession, or frame-dragging, effect for the first time. This occurs when a rotating black hole warps the fabric of spacetime, influencing the paths of nearby matter like stars. The event, detailed in a study published in Science Advances, centered on AT2020afhd, a tidal disruption event where a star was torn apart by a supermassive black hole.
The research, led by the National Astronomical Observatories at the Chinese Academy of Sciences with contributions from Cardiff University, tracked signals from the star's remnants. As the debris formed a spinning accretion disk around the black hole, powerful jets were ejected at nearly the speed of light. Researchers noted a synchronized wobble in the disk and jets, repeating every 20 days, captured through X-ray data from the Neil Gehrels Swift Observatory and radio observations from the Karl G. Jansky Very Large Array.
Electromagnetic spectroscopy further analyzed the material's composition and behavior, confirming the frame-dragging signal. This effect, first theorized by Albert Einstein in 1913 and formalized by Josef Lense and Hans Thirring in 1918, demonstrates how a spinning massive object generates a gravitomagnetic field, akin to a rotating charged object creating a magnetic field.
Dr. Cosimo Inserra, a co-author from Cardiff University, described the finding: "Our study shows the most compelling evidence yet of Lense-Thirring precession—a black hole dragging spacetime along with it in much the same way that a spinning top might drag the water around it in a whirlpool." He added that unlike prior tidal disruptions with steady signals, AT2020afhd's variability strengthened the evidence for this dragging effect, offering a novel way to probe black holes.
These observations not only validate key aspects of general relativity but also advance understanding of accretion physics and jet-launching mechanisms in black holes.