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GCN Circular 30954

Subject
AMON IC_HAWC NuEm-211020A: No neutrino counterpart detected with ANTARES
Date
2021-10-21T14:30:28Z (2 years ago)
From
Antoine Kouchner at ANTARES Collaboration <kouchner@apc.in2p3.fr>
Alexis Coleiro (APC/Universite de Paris) and Damien Dornic (CPPM/CNRS) on behalf of the ANTARES Collaboration. 

Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported AMON IC-HAWC coincidence alert NuEm-211020A (https://gcn.gsfc.nasa.gov/gcn3/30950.gcn3).

No up-going muon neutrino candidate events were detected within 3 degrees from the coincidence coordinate over a time period [10h52 - 14h13 UT] corresponding to 55.8% of the HAWC transit time mentioned in the AMON notice, during which the potential source remained visible in the up-going field of view of ANTARES.

This leads to a preliminary 90% confidence level upper limit on the muon neutrino radiant fluence from a point source located at the coordinates of the coincidence as reported by AMON, of about 15 GeV.cm^-2 over the energy range 4 TeV - 4 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and about 26 GeV.cm^-2 (750 GeV - 380 TeV) for an E^-2.5 spectrum. These indicative limits have been computed for the end of the HAWC transit time.

A search over an extended time window of +/-1 day has also yielded no detection (45% visibility).

ANTARES (https://antares.in2p3.fr) is the largest undersea neutrino detector (Mediterranean Sea) and it is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is about 0.5 degrees. In the range 1-100 TeV ANTARES has a competitive sensitivity to this position in the sky.
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