Archival Search for IceCube Sub-TeV Neutrino Counterparts to Sub-Threshold Gravitational Wave Events from the Third Observing Run of the LIGO-Virgo-KAGRA

Abstract: The IceCube Neutrino Observatory actively participates in multimessenger follow-ups of gravitational-wave (GW) events. With the release of the Gravitational-Wave Transient Catalogue (GWTC)-2.1 and -3, the sub-threshold GW event information from the third observation run of the LIGO-Virgo-KAGRA (LVK) detectors is publicly available. These sub-threshold GWs are identified via template-based and minimally modelled search pipelines. Neutrino counterparts can enhance their astrophysical significance and improve their localisation. In this contribution, we propose a catalogue-based search for sub-TeV neutrino counterparts to sub-threshold GWs. For this search, we use archival data from IceCube's dense infill array, DeepCore. Using the unbinned maximum likelihood method, we search for correlation between IceCube sub-TeV neutrinos and the $\sim$ 100 most significant sub-threshold GW source candidates. With this study, we aim to contribute to the ongoing efforts to identify common astrophysical sources of neutrinos and GWs. We present the current status of this search and its role in advancing multimessenger astronomy, paving the way for deeper exploration of GW events and their sources.