GCN Circular 22019

Damien Dornic (CPPM / CNRS), Alexis Coleiro (APC / IFIC)  report on behalf of the ANTARES Collaboration:

Using online data from the ANTARES detector, we have performed a follow-up analysis of the recently reported high-energy starting event (HESE) neutrino IceCube-171015 (AMON IceCube HESE 56068624_130126). The reconstructed origin was 24.5 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 (100% visibility probability). A search on an extended time window of +/- 1 day (58% visibility probability) has also yielded no detection.

This yields a preliminary 90% confidence level upper limit on the muon-neutrino fluence from a point source of 14 GeV.cm^-2 over the energy range 2.7 TeV - 2.8 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and 27 GeV.cm^-2 (440 GeV - 240 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.