Search for gravitational wave bursts from Soft Gamma Repeaters

We present the results of a LIGO search for short-duration gravitational waves associated with Soft Gamma Repeater (SGR) bursts, and a method for calibrating gravitational wave detectors via photon actuators.;Photon calibrators provide an independent calibration of LIGO's three gravitational wave detectors. Their nominal 2σ confidence error bars are currently estimated to be ∼3%. The photon calibrators have provided a valuable check on the official calibration, uncovering problems that may otherwise have gone unnoticed. We also present the first gravitational wave search sensitive to neutron star f-modes, usually considered the most efficient gravitational wave emitting modes. We find no evidence of gravitational waves associated with any SGR burst in a sample consisting of the 2004 December 27 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14 which occurred during the first year of LIGO's fifth science run. Gravitational wave strain upper limits and model-dependent gravitational wave emission energy upper limits are estimated for individual bursts using a variety of simulated waveforms. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient gravitational wave amplitudes published to date. We find upper limit estimates on the model-dependent isotropic gravitational wave emission energies (at a nominal distance of 10 kpc) between 3 × 1045 and 9 × 1052 erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models.