Search for Long-Transient Gravitational Waves from Newborn Magnetars Triggered by UV Counterparts

Newborn magnetars, formed in core-collapse supernovae or neutron star mergers, are expected to emit long-transient gravitational waves (lasting hours to days) as they spin down. If detected, these signals would provide insights into the extremely dense nuclear matter and strong magnetic fields. We describe an optimized semi-coherent search pipeline, GFH-v2, triggered by UV shock breakouts. The method has been tested using simulated signals in LIGO O3 data using parameters motivated by the recent supernova event SN 2023ixf, and a dedicated search targeting this event is planned.