Cygnus X-3: Upper limits from a neutrino search with IceCube
ATel #17661; Yuhua Yao (University of Wisconsin-Madison), Justin Vandenbroucke (University of Wisconsin-Madison) for the IceCube Collaboration
on 9 Feb 2026; 17:30 UT
Credential Certification: Justin Vandenbroucke (justin.vandenbroucke@wisc.edu)
Subjects: Neutrinos, Binary
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 microquasar Cygnus X-3 following reports from SVOM/ECLAIRs (ATel #17585), RATAN-600 (ATel #17600), Nasu (ATels #17605, #17637) in a time range of two weeks to cover the reported emission phases in radio and gamma-rays (2026-01-10 00:00:00.00 UTC to 2026-01-24 00:00:00.00 UTC), during which IceCube was collecting good quality data.
For this search, we report a p-value of 1.0 with respect to an atmospheric background-only hypothesis. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/dE = 7.2e-2 GeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are between approximately 700 GeV and 400 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)
