Ghost particle of a star crushed by a black hole reveals a cosmic particle accelerator


A team of scientists has detected the presence of a high-energy neutrino, a particularly elusive particle, following the destruction of a star by being consumed by a dungeon. This discovery, reported in the journal Nature astronomy, sheds new light on the origins of ultra-high-energy cosmic rays, the highest-energy particles in the Universe.

The work, which included researchers from more than two dozen institutions, including New York University and from Germany DESY research center, focused on neutrinos, subatomic particles that are produced on Earth only in powerful accelerators.

Neutrinos, as well as the process of their creation, are difficult to detect, which is why their discovery, along with that of ultra-high-energy cosmic rays (UHECR), is noteworthy.

Accretion disk around the supermassive black hole

Heart of Darkness: A view of the accretion disk around the supermassive black hole, with jet-like structures moving away from the disk. The extreme mass of the black hole bends spacetime, allowing the far side of the accretion disk to look like an image above and below the black hole. Credit: DESY, Scientific Communication Laboratory

“The origin of high-energy cosmic neutrinos is unknown, primarily because they are notoriously difficult to pin down,” explains Sjoert van Velzen, one of the lead authors on the paper and a postdoctoral fellow in the NYU Department of Physics at the time of discovery. . “This result would be only the second time that high-energy neutrinos have been traced back to their origin.”

Previous research by van Velzen, now at Leiden University in the Netherlands, and NYU physicist Glennys Farrar, co-author of the new Nature astronomy paper, found some of the first evidence of black holes destroying stars in what are now known as tidal disruption events (TDE). These findings set the stage to determine whether TDEs could be responsible for producing UHECR.

Research reported in Nature astronomy offered support for this conclusion.

Crushed Star Ghost Particle

The Smoking Gun: After the supermassive black hole tore through the star, about half of the star’s debris was spewed out into space, while the rest formed a bright accretion disk around the black hole. The system glowed brightly at many wavelengths and is believed to produce energetic outflows, jet-shaped, perpendicular to the accretion disk. A powerful central engine near the accretion disk spewed out these fast subatomic particles. Credit: DESY, Scientific Communication Laboratory

Previously, the IceCube Neutrino Observatory, a National Science Foundation-supported detector located at the South Pole, reported the detection of a neutrino, the trajectory of which was later tracked by the Zwicky Transient Facility at Caltech’s Palomar Observatory.

Specifically, their measurements showed a spatial coincidence of a high-energy neutrino and the light emitted after a TDE, a star consumed by a black hole.

“This suggests that these star-crushing events are powerful enough to accelerate high-energy particles,” explains van Velzen.


As the star approaches the black hole, enormous tidal forces stretch it further and further until it is finally destroyed. Half of the stellar debris is thrown into space, while the remaining part forms a rotating accretion disk from which two strong streams of matter shoot up and down. The system acts as a powerful natural particle accelerator. Credit: DESY, Scientific Communication Laboratory

“Discovering neutrinos associated with TDE is a breakthrough in understanding the origin of the high-energy astrophysical neutrinos identified by the IceCube detector at the South Pole, whose sources have so far been elusive,” adds Farrar, who proposed in a paper by 2009 that UHECRs could be accelerated in TDE. “The neutrino-TDE coincidence also sheds light on a decades-old problem: the origin of ultra-high energy cosmic rays.”

Reference: February 22, 2021, Nature astronomy.
DOI: 10.1038 / s41550-020-01295-8

The research was supported by grants from the National Science Foundation (CAREER Grant 1454816, AAG Grant 1616566, PIRE Grant 1545949, NSF Grant AST-1518052)



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