LIGO/Virgo S200105ae : no neutrino counterpart candidate in ANTARES search

Using on-line data from the ANTARES detector, we have performed a follow-up analysis of the recently reported LIGO/Virgo S200105ae subthreshold event using the 90% contour of the Initial GW_SKYMAP probability map provided by the GW interferometers (GCN#26640 <https://gcn.gsfc.nasa.gov/gcn3/26640.gcn3>). The ANTARES visibility at the time of the alert, together with the 50% and 90% contours of the probability map are shown at http://antares.in2p3.fr/GW/S200105ae_Initial.png <http://antares.in2p3.fr/GW/S200105ae_Initial.png>. Considering the location probability provided by the LIGO/Virgo collaborations, there is a 35.6% chance that the GW emitter was in the ANTARES **upgoing** field of view at the time of the alert. No up-going muon neutrino candidate events were recorded in the ANTARES sky during a +/-500s time-window centered on the time 2020-01-05 16:24:26 and in the 90% contour of the S200105ae event. The expected number of atmospheric background events in the region visible by ANTARES is 2.43e-03 in the +/- 500s time window. An extended search during +/- 1 hour gives no up-going muon neutrino coincidence. The expected number of atmospheric background events in the region visible by ANTARES is 1.75e-02 in this larger time window. ANTARES is the largest undersea neutrino detector, installed in the Mediterranean Sea, and it is primarily sensitive to 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.