An All-Sky Search for Continuous Gravitational Waves

2022
157 pages
Supervisor:
Thesis: PhD
  • Michigan U.
(2022)
  • Published: 2022

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Abstract: (Michigan U.)
The Laser Interferometer Gravitational-Wave Observatory (LIGO) experiment made the first ever discovery of gravitational waves in 2016 when it detected radiation from the merger of two black holes. Since then, LIGO and other gravitational wave experiments like VIRGO have made many more detections of other compact binary mergers. Compact binary mergers, continuous waves, bursts, and stochastic waves are the four broad sources of gravitational waves. Continuous waves are nearly monochromatic gravitational waves expected to be emitted by fast-spinning, nonaxisymmetric neutron stars. These signals are believed to be much weaker and so far have not been detected. In this work, we discuss an all-sky search for such radiation from isolated neutron stars using data collected from April to September, 2019 of the third LIGO observation run O3. Our search covers the frequency band 20-2000 Hz with a frequency time derivative in the range [-1.0, +0.1] x 1e-8 Hz/s. We obtain the lowest upper limits near 200 Hz with the best-case (circularly polarized) and worst-case (linearly polarized) being ~ 6.3 x 1e-26 and ∼ 1.7 x 1e-25 respectively. We present search methods, parameter space, and strategies used. We also discuss validation studies carried out and present results from the search. While we failed to detect a true signal, at the time of publication, we set the strictest upper limits on gravitational wave strain for a search covering a parameter space as wide as ours.
  • gravitational wave
  • continuous gravitational wave
  • LIGO
  • general relativity
  • neutron star
  • all-sky search
  • binary: compact
  • frequency: time dependence
  • gravitational radiation
  • LIGO