Evidence-based search method for gravitational waves from neutron star ring-downs

The excitation of quadrupolar quasinormal modes in a neutron star leads to the emission of a short, distinctive, burst of gravitational radiation in the form of a decaying sinusoid or ring-down. We present a Bayesian analysis method which incorporates relevant prior information about the source and known instrumental artifacts to conduct a robust search for the gravitational wave emission associated with pulsar glitches and soft gamma-ray repeater flares. Instrumental transients are modeled as sine-Gaussian and their evidence, or marginal likelihood, is compared with that of Gaussian white noise and ring-downs via the odds-ratio. Tests using simulated data with a noise spectral density similar to the LIGO interferometer around 1 kHz yield 50% detection efficiency and 1% false alarm probability for ring-down signals with signal-to-noise ratio rho=5.2. For a source at 15 kpc this requires an energy of 1.3x10(-5)Mc(2) to be emitted as gravitational waves.