On 1 October 2019, the IceCube Neutrino Observatory in Antarctica detected an exceptionally energetic 0.2 PeV neutrino. The Zwicky Transient Facility in California followed up seven hours later with wide-field observations of the sky at optical wavelengths. The facility observed optical emission in the 90% uncertainty region of the incoming neutrino.

After studying the large energy flux of the optical emission, its location within the reported uncertainty region of the sky where the high-energy neutrino came from, and some modeling results, researchers concluded that the two observations could be connected.1 The optical emission was caused by a bright transient phenomenon known as a tidal disruption event (TDE) that had first been observed one year before the neutrino.

TDEs occur when stars get close enough to supermassive black holes to experience spaghettification—the stretching and compressing of an object into a long, thin strand that is caused by the black hole’s...

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