Fermi J1820-1648: Upper limits from a neutrino search with IceCube
ATel #17707; Yuhua Yao (University of Wisconsin-Madison), Justin Vandenbroucke (University of Wisconsin-Madison) for the IceCube Collaboration
on 3 Mar 2026; 23:31 UT
Credential Certification: Justin Vandenbroucke (justin.vandenbroucke@wisc.edu)
Subjects: Neutrinos, Nova, Transient
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed a search for track-like muon neutrino events arriving from the direction of Fermi J1820-1648, a transient in the Galactic plane, following reports from Fermi LAT (ATels #17688, #17699), SOAR (ATel #17700) and other optical observations (ATels #17689, #17698), as well as SMA (ATel #17704). We searched in the time range of two weeks (2026-02-04 00:00:00.00 UTC to 2026-02-18 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 = 0.23 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 40 TeV and 20 PeV.
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.
