A high-energy neutrino coincident with a tidal disruption event!

Tracing back a ghostly particle from a star-shredding supermassive black hole, scientists have uncovered a gigantic cosmic particle accelerator. Some 700 million years ago, subatomic particles called neutrinos were hurled at nearly the speed of light toward Earth as a result of a peculiar cosmic encounter: A star wandered too close to a supermassive black hole and was ripped apart by the black hole’s colossal gravity.

Smoking gun: After the supermassive black hole tore the star apart, roughly half of the star debris was flung back out into space, while the remainder formed a glowing accretion disc around the black hole. The system shone brightly across many wavelengths and is thought to have produced energetic, jet-like outflows perpendicular to the accretion disc. A central, powerful engine near the accretion disc spewed out these fast subatomic particles. Credit: DESY, Science Communication Lab

Part of the star’s debris eventually fell back onto the black hole, causing a luminous flare. Scientists think that this phenomenon, called a tidal disruption event (TDE), could accelerate particles to nearly the speed of light. Those particles then collide with light or other particles to generate high-energy neutrinos.

A view of the accretion disc around the supermassive black hole, with jet-like structures flowing away from the disc. The extreme mass of the black hole bends spacetime, allowing the far side of the accretion disc to be seen as an image above and below the black hole. Credit: DESY, Science Communication Lab

Neutrinos are fundamental particles that far outnumber all the atoms in the universe but rarely interact with other matter. Astrophysicists are particularly interested in high-energy neutrinos, which have energies up to 1,000 times greater than those produced by the most powerful particle colliders on Earth. The first confirmed high-energy neutrino source, announced in 2018, was a type of active galaxy called a blazar.

The newly observed neutrino from the tidal disruption event is the first that can be traced back to a black hole. This scientific result was made possible by a large collaboration of theoretical and experimental scientists from Arizona State University, University of Wisconsin-Madison, Humboldt University, NASA, the Zwicky Transient Facility (ZTF) on Mount Palomar, the South Pole’s IceCube Neutrino Observatory and the Deutsches Elektronen-Synchrotron (DESY) in Germany.

The IceCube Neutrino Observatory is a facility of the U.S. National Science Foundation operated at the Amundsen-Scott South Pole Station under the U.S. Antarctic Program. Apart from IceCube and ZTF, the instruments Spectral Energy Distribution Machine (SEDM), Palomar 200-inch Hale Telescope (P200), Liverpool Telescope (LT), NASA’s Neil Gehrels Swift Observatory, Lowell Discovery Telescope, Lick Observatory Shane Telescope, Keck Telescope, ESA’s X-ray Multi-Mirror Mission (XMM-Newton), Karl G. Jansky Very Large Array (VLA), AMI Large Array (AMI-LA), MeerKAT, and NASA’s Fermi Large Area Telescope (Fermi-LAT) provided observational data for the study.

A team led by DESY scientist Robert Stein reports the observation in the journal Nature Astronomy. A theoretical model developed by Walter Winter, from DESY, and Professor Cecilia Lunardini, from Arizona State University’s Department of Physics, was published in the same issue of Nature Astronomy. Sources: news.asu.edu