The LIGO Scientific Collaboration has adopted a variety of data analysis techniques to target potential sources of gravitational waves, such as inspiraling binary systems, pulsars, transient bursts from core-collapse supernovae and the cosmological stochastic background. This talk provides an overview of these analysis methods and presents the most recent limits on the measurable rate of gravitational waves obtained with data from the LIGO second science run.
The Laser Interferometer Gravitational-wave Observatory (LIGO) Burst Analysis group is pursuing searches for unmodeled gravitational-wave transients of short duration (< 1 sec) in the 100-2000 Hz frequency band. Plausible sources of this type of signal are core-collapse supernovae and the merger and ringdown phases of coalescing binary systems. This talk presents new limits on the measurable rate of gravitational-wave bursts. Such limits constitute a significant improvement over the published results from the first LIGO science run, due to the increased observational time, better detector sensitivity and more sophisticated analysis techniques. In particular, the search in the 700-2000 Hz band has benefited from collaborations and data exchange with the TAMA (Japan) and GEO600 (Germany) interferometers, a major step forward in the implementation of a world-wide network of gravitational-wave detectors.
The Laser Interferometer Gravitational-wave Observatory (LIGO) Burst Analysis group is pursuing searches for unmodeled gravitational-wave transients of short duration (< 1 sec) in the 100-2000 Hz frequency band. Plausible sources of this type of signal are core-collapse supernovae and the merger and ringdown phases of coalescing binary systems. This talk provides a description of the burst analysis pipeline and the methods used to optimize the detection efficiency and suppress the false alarm rate with minimal assumptions about the signal's morphology. New limits on the measurable rate of gravitational-wave bursts will also be presented, as derived from data collected in LIGO's second science run. They constitute a significant improvement over the published results from the first science run, due to the increased observational time, better detector sensitivity and more sophisticated analysis techniques.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) consists of three interferometers of km-scale length located in Livingston, LA and Hanford, WA. As the detector construction has been completed and its commissioning is well under way, LIGO has started its quest to detect gravitational waves, extremely small ripples in the fabric of spacetime that originate from the universe's most violent events, such as supernova explosions and black-hole formation. This talk presents the LIGO detectors' performance through the first three science runs, the first scientific results and expected reach for Advanced LIGO. Particular emphasis will be given to the search for unmodeled bursts of gravitational waves, its challenges and the analysis methods we are implementing in our "eyes-wide-open" search.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) consists of three interferometers of km-scale length located in Livingston, LA and Hanford, WA. As the detector construction has been completed and its commissioning is well under way, LIGO has begun the acquisition of science quality data. This talk offers a description of the LIGO detectors performance through the first three science runs, the first scientific results and expected reach for Advanced LIGO. Particular emphasis will be given to the search for unmodeled bursts of gravitational waves: I will describe challenges and methods in this investigation, the current set of upper limits, and results from a search triggered by the recent, very bright gamma ray burst GRB030329.
The search for unmodeled gravitational wave bursts in LIGO relies on coincident detection in multiple interferometers. As no assumption is made about the event waveform or duration, the analysis pipeline requires loose coincidence in time, frequency and amplitude. Confidence in the resulting events and their waveform consistency is established through a time-domain coherent analysis: the "r-statistic test". This talk introduces the burst analysis pipeline and presents a performance study of the post-coincidence steps, applied to lowthreshold/high-false-rate background events from the LIGO S2 playground dataset. Particular emphasis will be given to the r-statistic test, its ability to suppress the background false rate, and its efficiency at detecting simulated bursts of different waveforms close to the S2 sensitivity curve.
The burst search in LIGO relies on coincident detection in multiple interferometers. As no assumption is made about the event waveform or duration, the analysis pipeline requires loose coincidence in time, frequency and amplitude. Confidence in the resulting events and their waveform consistency is established through a time-domain coherent analysis: the "r-statistic test". This talk presents a performance study of the post-coincidence steps applied to low-threshold/high-false-rate background events from the LIGO S2 playground dataset. Particular emphasis will be given to the r-statistic test, its ability to suppress the background false rate, and its efficiency at detecting simulated bursts of different waveforms close to the S2 sensitivity curve.
The LIGO burst search pipeline identifies short time segments (< 1 s) during which anomalies have occured in the strain data at multiple interferometers. No assumption is made on the event waveform or duration. This talk presents a test to verify the consistency of waveforms in burst candidate events at pairs of interferometers. The test is based on the r-statistic, or time domain linear cross correlation. After non-stationary lines are removed from the strain data, we introduce time lags between interferometers. We construct a distribution of the r-statistic over integration times of a few ms order and compute a maximum correlation confidence and the corresponding time lag between signals at different interferometers. The talk describes the conditioning techniques and how the various parameters in the test have been tuned. It also presents performance studies with injection of simulated signals in the LIGO data stream, for multiple combinations of interferometers.
LIGO and the LSC have been preparing for the search of burst-like events in the first LIGO science data. This talk offers an overview of the goals of the burst search and provides a description of the different methods used to generate triggers from the raw time series. It also introduces the infrastructure of our prototype burst analysis pipeline, which brings together triggers from the gravitational wave and diagnostics channels, in a statistically defined veto strategy, and then uses a multiple interferometer coincidence mechanism to identify candidate burst events. Various aspects of the burst analysis, such as the identification of the detector stationarity and gaussianity, will be discussed, together with strategies in the determination of of background, upper limits and efficiency estimation, which are essential for the interpretation of the results and the reach of astrophysical conclusions.