Doctor of Philosophy (PhD)
Physics and Astronomy
One hundred years after Albert Einstein predicted the existence of gravitational waves as a result of his theory of general relativity, the Laser Interferometer Gravitational-Wave Observatory (LIGO), made the first direct detection of a gravitational-wave signal from a binary black hole merger, GW150914. GW150914 was found not only by search methods specifically developed to find the distinctive waveform produced by coalescing binaries, but also by generic searches designed to find any arbitrary short-duration signal in the LIGO data. The impact of noise on the searches must be carefully investigated in order to reduce the search background and enable confident gravitational-wave detections. In this dissertation, I will present my work on characterizing transient noise sources in the detectors and implementing data quality vetoes to reduce their effects on the generic transient gravitational-wave searches. Chapters 3 and 4 describe my work on the data quality of the searches for generic transient gravitational waves. I worked on the development of data quality vetoes during the first observing run and the decisions about which vetoes to implement in the transient searches. I also analyzed the transient noise sources that the vetoes were unable to eliminate, using statistical methods to search for potential instrumental causes. Since the development of data quality vetoes requires a thorough understanding of every component of the detectors, I have also conducted a detailed investigation into the transients in the suspension systems used to isolate the LIGO optics from seismic motion. Chapter 5 presents the details of this work. The first gravitational wave detection was only the beginning an exciting era of gravitational-wave astronomy that will give us a new way of understanding the universe. Even in the first observing run, a second binary black hole merger was observed. The methods used in this dissertation to investigate and reduce background noise will continue to play an important role in making these detections possible. As the detectors improve in the future and continue to take data, more signals will be detected, bringing us a wealth of new information about black holes and other types of sources.
Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Walker, Marissa, "The Effects of Instrumental Noise on Searches for Generic Transient Gravitational Waves in Advanced LIGO" (2017). LSU Doctoral Dissertations. 4349.