NASA
Discovery identified during an extreme event in which a star was destroyed when it got too close to a supermassive black hole.
Astronomers observed, for the first time, the space-time “oscillating” in the vicinity of a rapidly rotating black hole — an effect predicted more than a century ago by theory of relativity of Albert Einstein.
The discovery was identified during an extreme event in which a star was destroyed when it got too close to a supermassive black hole.
The constitutes the first direct detection of a type of spacetime distortion known as Lense–Thirring precession, or “reference dragging” (frame-dragging). This phenomenon describes how the rotation of a black hole “twists” the fabric of space-time around it, dragging nearby matter and causing the orbits of gas and debris to gradually wobble.
The team analyzed an object called AT2020afhd. This is a tidal disruption event (TDE), in which a star is torn apart by the intense gravitational forces of a black hole.
As the star was torn apart, some of its debris formed a rapidly rotating accretion disk around the black hole. At the same time, jets of material were launched at speeds close to light, describes the .
By studying repetitive patterns in the X-ray and radio signals, the researchers concluded that both the disk and the jet were oscillating in a coordinated fashion, on a cycle of about 20 dias — a signature compatible with the dragging of spacetime by a rotating object.
The idea that gravity could have effects associated with rotation began to be explored by Einstein still in 1913, being described mathematically by Josef Lense and Hans Thirring in 1918.
These new observations reinforce a central prediction of general relativity and open a way to measure the rotation of black holes, understand how matter falls into these objects and investigate how relativistic jets are launched.
To detect the signal, the team used X-ray observations from the Neil Gehrels Swift Observatory and radio data from the Karl G. Jansky Very Large Array. Scientists also analyzed the composition and behavior of the surrounding material using spectroscopy, in order to characterize the structure of the debris and confirm the underlying physical process.
According to the authors, the case of AT2020afhd stands out for showing rapid variations in radio signalunlike other previously studied TDEs, which helped support the interpretation that the observed effect results from the “drag” of space-time by the black hole.
