Supermassive black holes tear apart stars and “pull them into spaghetti,” with some of the debris forming glowing accretion disks and the rest being thrown back into the surrounding space while energetic particles are ejected in a vertical direction.
Neutrinos are one of the fundamental particles that make up the world, far outnumbering all kinds of atoms, but they rarely interact with other matter. Astronomers are particularly interested in the high-energy neutrinos that come from the universe and visit Earth because they carry more than a thousand times the energy of particles that the most powerful particle colliders on Earth can produce, but are difficult to detect.
A study published Feb. 22 in the journal Nature Astronomy finds the first connection between a high-energy neutrino signal and a tidal disruption event in a distant galaxy. Robert Stein, one of the study’s authors, said, “This is the first present-day detection of neutrinos associated with a tidal disruption event (TDE), which is valuable evidence.”
Most of the neutrino rays that reach Earth come from the Sun, but occasionally neutrino detectors find neutrinos from the distant universe. This study reveals that a high-energy neutrino, IC191001A, detected on Oct. 1, 2019, by the IceCube Neutrino Observatory in Antarctica, is supposed to come from a particle emitted by a black hole tearing apart a star nearly 700 million light-years away from Earth.
Star “pulled into spaghetti” by black hole
What astronomers call a tidal disruption event is when a smaller object passing by a much more massive object is stretched, or even torn apart and destroyed, by the pull of a huge gravitational force. The most common scenario is when a star gets too close to a black hole and is torn apart.
When a star gets too close to a black hole, one end of the star is subjected to more gravitational force than the other, which has the effect of being stretched,” Stan said. As the star continues to get closer, this stretching effect becomes more and more extreme, eventually causing the star to be torn apart, and a tidal disruption event occurs.”
“The process is the same as for ocean tides on Earth (which occur when pulled by the Moon), but fortunately for us, the Moon’s gravity is not strong enough to stretch or tear the Earth apart.”
But the situation is much more serious for stars close to black holes. As an October 2020 study revealed, the ESO telescope observed a star being “stretched into spaghetti” by a black hole.
The strength of multi-channel signal observations
Astronomers don’t know much about tidal disruption events yet,” Stan said. The neutrinos detected are likely high-speed particles ejected from the accretion disk around the giant black hole at the center of the galaxy. From the analysis of the multi-channel information of radio waves, light waves and ultraviolet waves, we are more confident that the tidal disruption event is like a giant particle gas pedal.”
Stan’s “multi-channel information” observation refers to the fact that on April 9, 2019, the Palomar Observatory in California detected a lightwave signal from a tidal disruption event AT2019dsg. Analysis showed that it came from a lightwave signal 690 million light-years away in the constellation Delphinus. The analysis shows that it comes from an unnamed galaxy in the constellation Delphinus, 690 million light-years away.
Just seven hours after the discovery of high-energy neutrinos was announced at the South Pole Observatory in October, the researchers found two signals coming from the same direction in the sky.
Co-investigator Bradley Cenko of the University of Maryland said, “Tidal disruption events are extremely rare, occurring only once in about 10,000 to 100,000 years in galaxies like our own Milky Way.”
“The multi-signal channel observations are useful, and we’ve predicted before that high-energy neutrinos are associated with tidal disruption events, and this is the first Time we’ve found evidence of a link between them, which is so exciting.”
“Without the signal of the tidal disruption event, this neutrino signal is isolated; without the neutrino signal, this signal of the tidal disruption event is also isolated information. Only by combining the signals from multiple channels of observation can we find more information within these types of astronomical events.”
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