IceCube researchers detect a rare type of energetic neutrino sent from powerful astronomical objects

• In fact, only one of them is likely to lightly tap an atom in your body in your entire lifetime.
• While much rarer, these energetic neutrinos are more likely to crash into something and create a signal that physicists like me can detect.
• IceCube, one such experiment, documented an especially rare type of particularly energetic astrophysical neutrino in a study published in April 2024.

IceCube observatory

• The IceCube Neutrino Observatory is the 800-pound gorilla of large neutrino experiments.
• But the tau neutrino, one type of particularly energetic neutrino, has eluded IceCube – until now.

Neutrino flavors

• When a neutrino bangs into another particle, it usually produces a charged particle that corresponds with its flavor.
• A muon neutrino produces a muon, an electron neutrino produces an electron, and a tau neutrino produces a tau.
• The third flavor of neutrino, the tau neutrino, is the chameleon of the trio.
• One tau neutrino can appear as a track of light, while the next can appear as a ball.

Energetic tau neutrinos

• This data confirms IceCube’s earlier discovery of astrophysical neutrinos, and they confirm a hint that IceCube previously picked up of astrophysical tau neutrinos.
• In particular, the detection of astrophysical tau neutrinos confirms that energetic neutrinos from distant sources change flavor, or oscillate.

• As IceCube and other neutrino experiments gather more data, and scientists get better at distinguishing the three neutrino flavors, researchers will eventually be able to guess how neutrinos that come from black holes are produced.
• There will always be fewer energetic tau neutrinos and their muon and electron cousins compared with the more common neutrinos that come from the Big Bang.

Doug Cowen receives funding from the National Science Foundation.