Astronomers at Cardiff University discovered a strange twisted motion in the orbits of two colliding black holes. This strange phenomenon was predicted by Einstein's gravitational theory of . Their research report says this is the first time this effect known as "precession" is seen in a black hole, where the speed of distortion is 10 billion times faster than previous observations. Led by Professor Mark Hannam, Dr. Charlie Hoy and Dr. Jonathan Thompson, the study was published October 12 in the journal Nature.
Advanced LIGO and Virgo detectors discovered this "twin" black hole system through gravitational waves in early 2020. One of the black holes is estimated to be about 40 times the mass of our sun, and may be the fastest-rotating black hole found through gravitational waves. In addition, contrary to all previous observations, this fast-rotating black hole distorts space and time so much that the entire orbit of the binary stars sways back and forth.
Laser Interferometric Gravitational Wave Observatory (LIGO for short) is the world's largest gravitational wave observatory. It is a miracle of precision engineering, consisting of two huge laser interferometers, 3000 kilometers apart. LIGO uses the physical properties of light and space itself to detect and understand the origin of gravitational waves.
This form of precession is unique to Einstein's general theory of relativity . These results confirm that it exists in the most extreme physical event we can observe, the collision of two black holes.
"We have always believed that binary black holes can do this," said Professor Mark Hannam of Cardiff University's Gravity Exploration Institute. "Since the first time we detected gravitational waves, we've been hoping to find an example. We had to wait five years, wait for more than 80 separate detections, but in the end we had one!"
An example of premature aging that is closer to reality is the swing of the gyro, which may swing every few seconds. By contrast, precession in general relativity is usually so weak that it is impossible to detect. In the fastest example previously measured from an orbital neutron star known as the "Twins" pulsar , the orbit takes more than 75 years to move forward. The black hole binary star in this study, commonly known as GW200129 (named after the date it was observed, January 29, 2020), advances several times a second - an effect that is 10 billion times stronger than previously measured.
also from Cardiff University explains Dr. Jonathan Thompson. "This is a very tricky effect and is difficult to identify. Gravitational waves are extremely weak and detecting them requires the most sensitive measuring instruments in history. Progress is a weaker effect buried in an already weak signal, so we have to do a careful analysis to discover it."
Gravitational waves were predicted by Einstein in 1916. They were first detected directly from the merger of two black holes by advanced LIGO instruments in 2015, and this breakthrough discovery led to the 2017 Nobel Prize . Gravitational wave astronomy is now one of the most dynamic scientific fields, with a network of advanced LIGO, Virgo and KAGRA detectors operating in the United States, Europe and Japan. So far, there have been more than 80 detection results. All of these are merged black holes or neutron stars .
"So far, most of the black holes we found with gravitational waves have rotated quite slowly," said Dr. Charlie Hoy, a researcher at Cardiff University in the study and now a researcher at the University of Portsmouth. "The larger black hole in this binary, with a mass of about 40 times that of the Sun, rotates almost at a physically possible speed. Our current model of how the binary is formed shows that this binary is extremely rare, perhaps a thousandth of an event. Or it may be a signal that our model needs to change." The
International Gravitational Wave Detector Network is currently being upgraded and will begin the next search of the universe in 2023. They may find hundreds of collisions of black holes again. These new data will tell scientists that GW200129 is a rare exception or a sign that our universe is even stranger than they thought.
