NGC 1275: Upper limits from a neutrino search with IceCube
ATel #18018; Sam Hori (University of Wisconsin-Madison), Justin Vandenbroucke (University of Wisconsin-Madison)
on 28 Aug 2026; 04:57 UT
Credential Certification: Justin Vandenbroucke (justin.vandenbroucke@wisc.edu)
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed a search for track-like muon neutrino events arriving from the direction of the radio galaxy NGC 1275, following reports of a hard gamma-ray flare from Fermi-LAT (ATels #17937, #17943) and LHAASO (ATel #17957). We analyzed a time window of 21 days (2026-07-25 12:00:00 UTC to 2026-08-15 12:00:00 UTC), during which IceCube was collecting good quality data.
We report a p-value of 1.0, consistent with an atmospheric background-only hypothesis. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/dE = 6.8e-2 cm^-2 at 90% confidence level, for an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum have energies between approximately 650 GeV and 350 TeV.
The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
