TITLE:   GCN CIRCULAR
NUMBER:  28946
SUBJECT: IceCube-201120A: Upper limits from a search for additional neutrino events in IceCube
DATE:    20/11/23 21:10:01 GMT
FROM:    Alex Pizzuto at ICECUBE/U of Wisconsin  <pizzuto@wisc.edu>

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

IceCube has performed a search for additional track-like muon neutrino events arriving
from the direction of IceCube-201120A (https://gcn.gsfc.nasa.gov/gcn3/28927.gcn3) in a time
range of 2 days centered on the alert event time (2020-11-19 09:44:40.56 UTC to 2020-11-21 09:44:40.56 UTC) during which IceCube was collecting good quality data. Excluding the
event that prompted the alert, three additional track-like events are found in spatial coincidence
with the 90% containment region of IceCube-201120A. We find that these data are consistent with atmospheric background expectations, with a p-value of 1.0. We accordingly derive a time-integrated muon-neutrino flux upper limit at the alert position of E^2 dN/dE = 5.8 x 10^-5 TeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are approximately between 1 TeV and 500 TeV.

A subsequent search was performed to include the month of data prior to the alert event (2020-10-21 09:44:40.56 UTC to 2020-11-21 09:44:40.56 UTC). In this case, we report a p-value of 1.0, consistent with no significant excess of track-like events, and a corresponding time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) of
6.7 x 10^-5 TeV cm^-2 at the 90% CL.

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