Effects of transients in LIGO suspensions on searches for gravitational waves

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  • LIGO Scientific Collaboration
  • Virgo Collaboration

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  • Louisiana State University
  • California State University Fullerton
  • LIGO Livingston Observatory
  • California Institute of Technology
  • Syracuse University
  • LIGO Hanford Observatory
  • University of Glasgow
  • Massachusetts Institute of Technology
  • Columbia University
  • University of Western Australia
  • University of Florida
  • Albert-Einstein-Institut, Max-Planck-Institut für, Gravitationsphysik
  • University of Sheffield
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  • University of Sannio at Benevento
  • Complesso Universitario di Monte S.Angelo
  • University of Mississippi


This paper presents an analysis of the transient behavior of the Advanced LIGO (Laser Interferometer Gravitational-wave Observatory) suspensions used to seismically isolate the optics. We have characterized the transients in the longitudinal motion of the quadruple suspensions during Advanced LIGO's first observing run. Propagation of transients between stages is consistent with modeled transfer functions, such that transient motion originating at the top of the suspension chain is significantly reduced in amplitude at the test mass. We find that there are transients seen by the longitudinal motion monitors of quadruple suspensions, but they are not significantly correlated with transient motion above the noise floor in the gravitational wave strain data, and therefore do not present a dominant source of background noise in the searches for transient gravitational wave signals. Using the suspension transfer functions, we compared the transients in a week of gravitational wave strain data with transients from a quadruple suspension. Of the strain transients between 10 and 60 Hz, 84% are loud enough that they would have appeared above the sensor noise in the top stage quadruple suspension monitors if they had originated at that stage at the same frequencies. We find no significant temporal correlation with the suspension transients in that stage, so we can rule out suspension motion originating at the top stage as the cause of those transients. However, only 3.2% of the gravitational wave strain transients are loud enough that they would have been seen by the second stage suspension sensors, and none of them are above the sensor noise levels of the penultimate stage. Therefore, we cannot eliminate the possibility of transient noise in the detectors originating in the intermediate stages of the suspension below the sensing noise.

Bibliographic note

Effects of transients in LIGO suspensions on searches for gravitational waves, M. Walker et al, Review of Scientific Instruments 2017 88:12


Original languageEnglish
Article number124501
JournalReview of Scientific Instruments
Issue number12
Publication statusPublished - 1 Dec 2017

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