TITLE:   GCN CIRCULAR
NUMBER:  37686
SUBJECT: NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
DATE:    24/10/02 22:27:22 GMT
FROM:    Alicia Mand at IceCube/UW-Madison <aemand@wisc.edu>

The IceCube Collaboration (http://icecube.wisc.edu/) reports:

IceCube has performed a search for additional track-like muon neutrino events following the HAWC-IceCube alert NuEm-240926A ([GCN Notice](https://gcn.gsfc.nasa.gov/notices_amon_nu_em/0_164965.amon)), at the location of the blazar BZQ J0955+4532, which was observed by MASTER to switch from an off-state to a on-state in the optical band shortly after the HAWC-IceCube alert ([GCN Circular](https://gcn.nasa.gov/circulars/37617)). The search was performed using a time window of 4 weeks (2024-09-03 23:00:00.0 UTC to 2024-10-01 23:00:00.0 UTC), during which IceCube was collecting good quality data.

We find that the data are consistent with atmospheric background expectations, with a p-value of 1.0. We accordingly derive a time-integrated muon-neutrino flux upper limit at the location of this blazar of E^2 dN/ dE = 7.6 x 10^-2 GeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. The central 90% energy range of events IceCube would detect from a source at this declination with an E^-2 spectrum is approximately 600 GeV to 300 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)