Digging Deeper: Finding Sub-threshold Compact Binary Merger Events in LIGO Data<
Abstract
The LIGO and Virgo detectors have collected gravitational wave (GW) data from three separate observation runs since 2015, with the third run presently collecting data. There have been 10 signals from binary black hole mergers and one binary neutron star merger detected from the first two observation runs and many more from the third run. These detections were all found with high confidence based on their signal-to-noise ratio (SNR); however, there are likely many more less significant signals in the data with lower SNRs. A limitation in the SNR criteria arises when the accidental coincidence of "loud" glitches or other rare noise fluctuations in the LIGO detectors can result in high SNRs but are not the product of real GWs. We hope to improve the confidence in the detection or rejection of such sub-threshold (marginal) events with lower SNRs by computing the Bayesian coherence ratio (BCR): the odds between the hypothesis that the data comprise either a coherent compact-binary-coalescence signal in two or more detectors in Gaussian noise, or incoherent instrumental features, using parameter estimation. Single-detector events will not be possible for BCR analysis because coherence would be indeterminable. We present a BCR analysis done on event and background data as well as published O1 and O2 sub-threshold events. Initial results provide evidence that the BCR can distinguish between signal and incoherent noise given appropriate parameters, indicating a potential to improve sub-threshold event detections.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23510713G