The cosmos has delivered an extraordinary gift to scientists who have long sought to observe one of the most elusive phenomena in the universe. A study published in Science Advances reveals the first observations of a swirling vortex in spacetime, caused by a rapidly rotating black hole. This groundbreaking discovery confirms a century-old prediction by Albert Einstein.
The research, led by the National Astronomical Observatories at the Chinese Academy of Sciences and supported by Cardiff University, focuses on AT2020afhd, a tidal disruption event (TDE) where a star was torn apart by a supermassive black hole. The process, known as Lense-Thirring precession or frame-dragging, describes how black holes twist the spacetime around them, causing nearby objects like stars to wobble in their orbits.
Unveiling the Mysteries of Black Holes
The team observed that a swirling disk formed around the black hole from the remnants of the star, from which powerful jets of matter were ejected at nearly the speed of light. By analyzing rhythmic changes in both X-ray and radio signals emanating from the event, the researchers discovered that the disk and jet were wobbling in unison, repeating every 20 days.
First theorized by Einstein in 1913 and mathematically defined by Lense and Thirring in 1918, this observation confirms a prediction of general relativity, opening new avenues for studying black hole spin, accretion physics, and jet formation.
“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,” said Dr. Cosimo Inserra, a Reader in the School of Physics and Astronomy at Cardiff University and one of the paper’s co-authors.
Implications for Future Research
This discovery not only validates Einstein’s predictions but also provides insights into the nature of TDEs, where a star is shredded by the immense gravitational forces of a black hole. Unlike previous TDEs studied, which exhibited steady radio signals, AT2020afhd showed short-term changes, further confirming the frame-dragging effect and offering scientists a new method for probing black holes.
The team utilized X-ray data from the Neil Gehrels Swift Observatory and radio signal data from the Karl G. Jansky Very Large Array to identify the frame-dragging effect. Further analysis of the cosmic matter’s composition, structure, and properties through electromagnetic spectroscopy enabled them to describe and identify the process.
Understanding the Mechanics of the Universe
“By showing that a black hole can drag spacetime and create this frame-dragging effect, we are also beginning to understand the mechanics of the process,” Dr. Inserra explains. “So, in the same way a charged object creates a magnetic field when it rotates, we’re seeing how a massive spinning object – in this case, a black hole – generates a gravitomagnetic field that influences the motion of stars and other cosmic objects nearby.”
This discovery serves as a reminder of the vast opportunities that lie in understanding the universe’s extraordinary phenomena. As scientists continue to explore these cosmic wonders, they are better equipped to unravel the mysteries of black holes and the fundamental forces at play in the universe.
The paper, titled ‘Detection of disk–jet coprecession in a tidal disruption event’, is published in Science Advances, marking a significant milestone in astrophysics and offering a festive reflection on the wonders of the night sky.
