GCN Circular 21923

D. Dornic (CPPM/CNRS), A. Coleiro (APC/Universite Paris Diderot) on behalf of the ANTARES Collaboration:

Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported single high-energy (EHE) neutrino IceCube-170922A (AMON IceCube EHE 50579430_130033). The reconstructed origin was 14.2 degrees below the horizon for ANTARES.

No up-going muon neutrino candidate events were recorded within three degrees of the IceCube event coordinates during a +/- 1h time-window centered on the IceCube event time. A search on an extended time window of +/- 1 day has also yielded no detection (46% visibility probability).

This yields a preliminary 90% confidence level upper limit on the muon-neutrino fluence from a point source of 15 GeV.cm^-2 over the energy range 3.3 TeV - 3.4 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and 34 GeV.cm^-2 (450 GeV - 280 TeV) for an E^-2.5 spectrum.

ANTARES is the largest neutrino detector installed in the Mediterranean Sea, and is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range.  At 10 TeV, the median angular resolution for muon neutrinos is below 0.5 degrees. In the range 1-100 TeV, ANTARES has the best sensitivity to this position in the sky.