Systematic neutrino search narrows origins for high-energy cosmic particles
by Riko Seibo
Tokyo, Japan (SPX) Oct 28, 2025

A research team from Tohoku University led the first systematic optical search for counterparts to a high-energy neutrino multiplet event detected by the IceCube Neutrino Observatory. Multiplet events involve multiple neutrinos observed from a single direction in a short period, and may point to powerful cosmic phenomena such as supernovae or stars disrupted by black holes.

The team analyzed wide-field optical telescope data matching the time and location of the neutrino signals. No supernovae, tidal disruption events, or other explosive sources were found at the expected positions. The absence of visible transients allows researchers to set stronger limits on how bright and persistent such events might be if responsible for emitting neutrino multiplets.

"Although we didn't find any transient sources this time, our results show that even non-detections can provide powerful insights," said Toshikage. "They help us refine our models and guide future searches for the true sources of high-energy neutrinos."

The study, applying new search methods to multi-messenger data, was published in The Astrophysical Journal on October 23, 2025. The group plans to continue rapid optical observations triggered by future IceCube neutrino discoveries, aiming to further constrain the mechanisms producing the universe's most energetic particles.

Research Report:The First Search for Astronomical Transient as a Counterpart of a Month-timescale IceCube Neutrino Multiplet Event

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