IceCube Realtime Gravitational Wave Follow-up

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NOTE: on 6/18/2024 at 15:00 UTC (10:00 AM US-Central) there was an update to the schema to reflect the GCN core schema updates in v4.0.0. This affects the reporting of event angular error. Refer to the updated schema and updated example to see the for what is currently being sent on the gcn.notices.icecube.lvk_nu_track_search topic.

Note: On 9/26/2023 at about 20:30 UTC (3:30PM US-Central) there was an update to the script that sends results for these analyses over GCN-Kafka to fix small issues in format of results pointed out in this GitHub issue. Refer to the v3.0.0 schema and v3.0.0 example to see the updated contents [until 6/18/2024 - then see v4.0.0 (above)].

General information about the analyses

This webpage details the results of two searches for high-energy neutrinos using the IceCube Neutrino Observatory from gravitational wave events published in realtime by the LIGO, Virgo, and KAGRA collaborations (for LVK event information, see GraceDB). There are two follow-up methods used here: (1) a general transient search, using an unbinned maximum likelihood analysis, and (2) a Bayesian search assuming a binary merger scenario. For more information, see Abbasi et al. Astrophys.J. 944 (2023) 1, 80 and M. G. Aartsen et al 2020 ApJL 898 L10.

Both analyses are run on every type of LVK event (BNS, NSBH, and BBH). In O3, the results were sent via GCN Circular. In O4, they are automatically sent via GCN Notice over Kafka (see documentation on gcn.nasa.gov), and you can find the schema here. Low significance GW events are indicated with a grey background for that row in the table below, and can be hidden with the button.

Currently, the Bayesian search is running on all CBC events (low and high significance) and the generic transient search is running on all high significance alerts.

Explanation of parameters

• Event Name: Name of event sent by LVK, with the format SYYMMDDxx-#-TYPE. The SYYMMDDxx is the event name sent by LVK, the # the map iteration number used, and the TYPE the type of map, which can be Preliminary, Initial, or Update.
• Merger Time: time of the merger, in ISO format
• LVK GCN: link to LVK GCN Notice
• IceCube GCN: link to the IceCube GCN Notice (and Circular, if sent)
• Duration: Duration of the IceCube neutrino search (seconds)
• N Coincident Neutrinos: number of IceCube neutrinos that are spatially and temporally coincident with the LVK skymap
• IceCube Sensitivity: 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 GW skymap. It is given as a range [low sensitivity, high sensitivity] in GeV cm^-2 for a 1000 second time window.
• Neutrino Information: link to additional information about coincident neutrinos released for the event, if sent

Events are highlighted in red if retracted by LVK and in grey for low-significance alerts.

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