Searching for Gravitational-Wave Signals in KAGRA Using LIGO–Virgo Observations and Assessing Their Detectability

In this study, we use information on gravitational-wave events detected by LIGO and Virgo to examine a method for searching for low signal-to-noise-ratio gravitational-wave signals in KAGRA and to assess their detectability. Using the Bayes factor as the detection statistic, we compare its performance with that of conventional matched filtering through simulations assuming Gaussian noise. We further inject simulated gravitational-wave signals into real KAGRA data taken during the fourth observing run (O4) and evaluate the detection performance, taking into account the false alarm probability (FAP) and the effects of non-stationary noise. Through these studies, we assess the effectiveness of KAGRA follow-up searches for known gravitational-wave events.