GCN Circular 39428
Subject
LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
Date
2025-02-23T15:10:32Z (2 months ago)
From
Jessie Thwaites at IceCube/U Wisc-Madison <thwaites@wisc.edu>
Via
Web form
IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed an additional search [1] for track-like muon neutrino events consistent with the sky localization of gravitational-wave candidate S250206dm in a time range of -0.1 day, +14 days from the alert event time (2025-02-06 19:01:30.439 UTC to 2025-02-20 21:25:30.439 UTC).
During this time period IceCube was collecting good quality data. In this case, we report a p-value of 0.85, consistent with no significant excess of track events. IceCube's sensitivity assuming an E^-2 spectrum (E^2 dN/dE) to neutrino point sources within the locations spanned by the 90% spatial containment of the 7-Update map ranges from 0.028 to 1.010 GeV cm^-2 in this time window.
Searches for track-like muon neutrino events detected by IceCube consistent with the 7-Update skymap in a time range of 1000 seconds centered on the alert event time (2025-02-06 21:17:10.436 UTC to 2025-02-06 21:33:50.436 UTC) were also performed using two hypothesis tests. [1,2]. The first search is a maximum likelihood analysis which searches for a generic point-like neutrino source coincident with the given GW skymap. The second uses a Bayesian approach to quantify the joint GW + neutrino event significance, which assumes a binary merger scenario and accounts for known astrophysical priors, such as GW source distance, in the significance estimate [3].
For these searches we report an overall p-value of 0.021 for the generic transient search and 0.044 for the Bayesian search using the 7-Update map. These p-values measure the consistency of the observed track-like events with the known atmospheric backgrounds for this single map (not trials corrected for multiple GW events). These results are updated since GCN 39176 with the updated skymap. Further details are available at https://gcn.nasa.gov/missions/icecube. Additional details and updates will be posted at https://roc.icecube.wisc.edu/public/LvkNuTrackSearch/.
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.
[1] Abbasi et al. Astrophys.J. 944 (2023) 1, 80
[2] M. G. Aartsen et al 2020 ApJL 898 L10
[3] I. Bartos et al. 2019 Phys. Rev. D 100, 083017