According to research published in Science Advances, astronomers using the Karl G. Jansky Very Large Array and the Neil Gehrels Swift Observatory have recorded the first direct observational evidence of a spiraling spacetime swirl, known as frame-dragging or Lense-Thirring precession, around a rapidly spinning black hole during a tidal disruption event designated as AT2020afhd.
Detecting Frame-Dragging in AT2020afhd
The phenomenon of frame-dragging occurs when a massive, rotating object twists the fabric of spacetime around it, dragging nearby matter along in a manner comparable to a spinning top in a whirlpool. First proposed by Albert Einstein in 1913 and later formalized mathematically by Josef Lense and Hans Thirring in 1918, the effect generates a gravitomagnetic field that influences the motion of nearby stars and gas.
In the case of AT2020afhd, a supermassive black hole shredded a passing star, a catastrophic occurrence known as a tidal disruption event (TDE). As reported by the research team led by the National Astronomical Observatories at the Chinese Academy of Sciences and supported by Cardiff University, the remaining stellar material formed a spinning accretion disk that launched intense plasma jets at nearly the speed of light.
The 20-Day Cosmic Wobble Cycle
By tracking repeating patterns in X-ray and radio signals captured by the Very Large Array and the Swift Observatory, researchers discovered that both the accretion disk and the relativistic jet were wobbling in unison on a precise 20-day cycle.
Dr. Cosimo Inserra, a Reader in the School of Physics and Astronomy at Cardiff University and co-author of the study, stated that the findings offer the most compelling evidence yet of Lense-Thirring precession in action. Unlike previous tidal disruption events that exhibited steady radio profiles, the signals from AT2020afhd displayed short-term modulations that could not be explained solely by standard energy releases, thereby confirming the spacetime-dragging effect.
Observing Black Hole Outflows in Swift J1727.8-1613
In a separate astronomical breakthrough, researchers utilized the European Southern Observatory’s Very Large Telescope (VLT) to track the violent feeding cycle and subsequent mass ejections of Swift J1727.8-1613, located approximately 8,800 light-years away. The system generated some of the brightest X-ray emissions in Earth’s sky following an outburst in 2023.
Team leader Noel Castro Segura of the University of Warwick noted that observations of Swift J1727.8-1613 revealed that black holes operate less like simple bottomless pits and more like complex cosmic processing systems. As the black hole stripped material from a companion star, a significant fraction of the matter was not consumed. Instead, it was expelled back into space as high-speed plasma jets and powerful winds.
The research team discovered that the most massive outflows occurred during periods when the black hole’s feeding activity was much lower than previously anticipated. According to Kyle Solomons, a doctoral researcher at the University of Cape Town, the finale of a black hole outburst can match the intensity of its initial fireworks. The data suggests that the total mass ejected over time may equal the amount consumed, altering current scientific models of binary star evolution in galaxies.