The search for unmodeled gravitational-wave transients in the Advanced LIGO-Virgo Era
Name
1263579890-MIT.pdf
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24.32 MB
Format
Adobe PDF
Checksum (MD5)
9cc53b0db69faf2e78fbd633eec0d0fc
Author(s)
Lynch, Ryan Christopher.
Advisor(s)
Erotokritos Katsavounidis and Salvatore Vitale.
Date Issued
2018
Publisher
Massachusetts Institute of Technology
Abstract
Between 2015 and 2017, the era of gravitational-wave (GW) astronomy began in a spectacular fashion. The Advanced-era GW detectors directly observed GW transients from two types of compact-binary sources: binary black holes (e.g., GW150914) and binary neutron stars (e.g., GW170817). Compact-binary sources are well-studied theoretically with well-understood strain waverforms, and thus their detections with Advanced LIGO-Virgo has led to an enormous number of physical insights. Nevertheless, we expect transient GW sources with waveforms that are not fully modeled or are too quiet to be fully resolved may contain an abundant wealth of physical richness in their own right. This thesis explores how to confidently establish poorly-modeled and poorly-resolved, i.e., "unmodeled", GW transients as detections. We first develop a search algorithm that can be used to detect short-duration GW transients of general signal morphology. This algorithm was one of two independent algorithms to first detect the first GW detection, GW150914, in low-latency. After establishing how GW transients of arbitrary morphology can be detected, we turn our attention to the detection of quiet GW signals that are not fully resolvable. We first explore the prospect of using multi-messenger astronomy to elevate low-significance GW candidates to the status of confident detections. Then, we develop a statistical consistency test that can be used to detect populations of poorly-resolved GW candidates. We apply the new search algorithm and new statistical consistency test to data obtained in the first and second observing runs of the Advanced Detector Era. We show that standard compact-binary sources, such as GW150914, can be detected confidently using these methods. Although no non-compact-binary GW transients are detected, we use these new tools to set the strictest upper limits to date on the rate-density of non-compact-binary GW transients. Finally, we turn our attention to how future improvements to the Advanced Detectors, such as squeezed-light injection, will impact the science done with GW transients.
Description
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, September, 2018
Cataloged from the PDF version of thesis.
Includes bibliographical references (pages 227-238).
Subjects
Physics.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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