IMPROVING THE SENSITIVITY OF ADVANCED LIGO THROUGH DETECTOR CHARACTERIZATION

This dissertation focuses on the impact of detector characterization work on searches for gravitational waves from compact binary coalescences (CBCs) in Ad- vanced LIGO’s second observing run (O2). This observing run started on November 30, 2016, and lasted until August 25, 2017, and resulted in the identification of 8 unambiguous gravitational-wave signals, including the first observation of a binary neutron star merger. The role of detector characterization is to leverage knowledge of both the interferometers and the data in order to improve aLIGO’s ability to observe gravitational-waves.I focus on the construction of the O2 noise subtracted data set that was searched as a part of the LIGO-Virgo Collaboration’s first gravitational-wave catalog, GWTC- 1. This data set was processed with a noise subtraction pipeline to remove the excess noise identified at each interferometer that resulted in a 30% improvement in the sensitive volume that aLIGO was able to probe. Equally important to the finalized data set is the inclusion of data quality vetoes that indicate periods of instrumental artifacts.I also examine how these instrumental artifacts can mimic gravitational-wave waveforms and reduce the sensitivity of searches for CBC signals, with particular emphasis on the PyCBC pipeline. Understanding this connection is one of the key ways that gravitational waves are differentiated from instrumental artifacts. Finally, I detail the final results presented in the GWTC-1 catalog from a detector charac- terization perspective, and discuss how the efforts highlighted in this dissertation allowed for the detection of new gravitational-wave events and improved analyses of previously identified events.