Since the release of the Gravitational Wave Transient Catalogue GWTC-2.1 by
the LIGO-Virgo collaboration, sub-threshold gravitational wave (GW) candidates
are publicly available. They are expected to be released in real-time as well,
in the upcoming O4 run. Using these GW candidates for multi-messenger studies
complement the ongoing efforts to identify neutrino counterparts to GW events.
This in turn, allows us to schedule electromagnetic follow-up searches more
efficiently. However, the definition and criteria for sub-threshold candidates
are pretty flexible. Finding a multi-messenger counterpart via archival studies
for these candidates will help to set up strong bounds on the GW parameters
which are useful for defining a GW signal as sub-threshold, thereby increasing
their significance for scheduling follow-up searches. Here, we present the
current status of this ongoing work with the IceCube Neutrino Observatory. We
perform a selection of the sub-threshold GW candidates from GWTC-2.1 and
conduct an archival search for sub-TeV neutrino counterparts detected by the
dense infill array of the IceCube Neutrino Observatory, known as "DeepCore".
For this, an Unbinned Maximum Likelihood (UML) method is used. We report the
90% C.L. sensitivities of this sub-TeV neutrino dataset for each selected
sub-threshold GW candidate, considering the spatial and temporal correlation
between the GW and neutrino events within a 1000 s time window.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023).
See arXiv:2307.13047 for all IceCube contribution