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S5 LIGO all-sky burst search with the Q pipeline


This page summarizes the plans for an all-sky search for astrophysically unmodeled sources of gravitational-wave bursts such as those from core collapse supernovae, the merger of binary black holes, or unknown sources.

The search is performed on the first calendar year of S5 data using the Q Pipeline search algorithm. The Q Pipeline is a multi-resolution time-frequency search for excess signal energy, and is equivalent to a templated matched filter search for sinusoidal Gaussians in the whitened data stream.

The search takes advantage of the collocated LIGO Hanford detectors to improve both the sensitivity to gravitational-wave bursts and the rejection of instrumental artifacts.


Project name:
  • S5 LIGO all-sky burst search with the Q Pipeline
Scientific goals:
  • All-sky search for gravitational-wave bursts using the H1H2 and H1H2L1 networks.
  • Upper limits for a variety of simulated waveforms using loudest event statistic.
  • Follow-up of 100 most significant event by QScans and coherent consistency tests.
Data sets:
  • H1, H2, and L1 data from the first calendar year of S5:
    • Starting 2005-NOV-04 16:00 UTC (815155213)
    • Stopping 2006-NOV-14 18:00 UTC (847562414)
  • Detector networks:
    • H1H2 double coincident data set
    • H1H2L1 triple coincident data set
  • Uses h(t) time-domain calibrated data:
    • Version 2 calibration for tuning
    • Version 3 calibration for final analysis
  • Follow-up of significant events also uses:
    • Raw frame data for auxiliary detector and environmental scans
    • GEO h(t) data when available
  • We expect to extend the search using a similar tuning to the entire S5 data set
  • Virgo data will also be used for follow-up consistency testing once data sharing is approved
Analysis approach:
  • Uses the Q Pipeline search algorithm for gravitational-wave bursts
  • Data from the H1 and H2 detectors are combined to form two new data streams:
    • H+, which is the linear combination that maximizes the signal to noise ratio
    • H-, which is the linear combination that cancels any signal
  • There are two components to the search:
    • H1H2 double coincident search:
      Identifies statistically significant events in the H+ data stream for which the H- data stream is consistent with the expected detector noise.
    • H1H2L1 triple coincident search:
      Identifies statistically significant events in the L1 data stream that are coincident in time and frequency with events from the H1H2 double coincident search.
  • Upper limits are determined for both the H1H2 and H1H2L1 data sets using the loudest event statistic at the 90 percent confidence level.
  • The 100 most significant events from both the H1H2 and the H1H2L1 data sets are being followed up using:
    QScan to search for statistically significant signal content in auxiliary detector and environmental channels and to test for any data quality flags.
    QEvent to produce sky maps of gravitational-wave burst consistency, if data is available from a sufficient number of detectors.
Relationship to other projects:
Code reviewers:
Presentations and papers:
  • GWDAW 11 Presentation [PDF, PPT]
  • LSC November 2006 Meeting Presentation [PDF, PPT]
  • APS April 2006 Meeting Presentation [PDF, PPT]
  • LSC March 2006 Meeting Presentation [PDF, PPT]
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