[vsnet-grb-info 21122] Search for counterparts to IceCube-180908A with IceCube

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23220
SUBJECT: Search for counterparts to IceCube-180908A with IceCube
DATE:    18/09/11 02:30:37 GMT
FROM:    Alex Pizzuto at ICECUBE/U of Wisconsin  <pizzuto at wisc.edu>

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

We report on additional observations of IceCube-180908A, GCN 23214 by the IceCube Neutrino Observatory.

IceCube has performed a search for additional track-like muon neutrino events arriving from the direction of the IceCube-180908A alert (https://gcn.gsfc.nasa.gov/gcn3/23214.gcn3) in a time range of 2 days centered on the alert event time (2018-09-07 19:59:31.84 to 2018-09-09 19:59:31.84) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, two additional neutrino track events are found in spatial coincidence with IceCube-180908A with a p-value of 0.027 (1.9 sigma). Accordingly, these tracks would represent a time-integrated muon-neutrino flux normalization assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 1.39 x 10^-5 TeV cm^-2 (+2.20, -1.09) ( 4.46 x 10^-5 TeV cm^-2 flux upper limit at the 90% CL) for this observation period.
A subsequent search was performed to include the previous month of data (2018-08-08 19:59:31.84 to 2018-09-09 19:59:31.84). In this case, we report a p-value of 1.0, consistent with no significant excess of track events, and a corresponding time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 5.32 x 10^-5 TeV cm^-2.

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 at icecube.wisc.edu<mailto:roc at icecube.wisc.edu>.