Gravitational Wave Astrophysics: Instrumentation, Detector Characterization, and a Search for Gravitational Signals from Gamma-ray Bursts

In the coming years, the second generation of interferometric gravitational wave detectors are widely expected to observe the gravitational radiation emitted by compact, energetic events in the nearby universe. The field of gravitational wave astrophysics has grown into a large international endeavor with a global network of kilometer-scale observatories. The work presented in this thesis spans the field, from optical metrology, to instrument commissioning, to detector characterization and data analysis. The principal results are a method for the precise characterization of optical cavities, the commissioning of the advanced LIGO Output Mode Cleaner at the Hanford observatory, and a search for gravitational waves associated with gamma-ray bursts

Thermal effects in the Input Optics of the Enhanced Laser Interferometer Gravitational-Wave Observatory interferometers

We present the design and performance of the LIGO Input Optics subsystem as implemented for the sixth science run of the LIGO interferometers. The Initial LIGO Input Optics experienced thermal side effects when operating with 7 W input power. We designed, built, and implemented improved versions of the Input Optics for Enhanced LIGO, an incremental upgrade to the Initial LIGO interferometers, designed to run with 30 W input power. At four times the power of Initial LIGO, the Enhanced LIGO Input Optics demonstrated improved performance including better optical isolation, less thermal drift, minimal thermal lensing, and higher optical efficiency. The success of the Input Optics design fosters confidence for its ability to perform well in Advanced LIGO

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Progress on the Haystack Observatory Postprocessing System

The Haystack Observatory Postprocessing System (HOPS) is a multipurpose tool for post-correlation calibration and data analysis in Very-Long Baseline Interferometry experiments. The requirements on stations, baselines, and bandwidth for the Next Generation Event Horizon Telescope (ngEHT) have motivated a significant refactoring of the HOPS codebase. In this paper, we present the requirements, specifications, and design of HOPS 4.0 and the current state of the refactoring, and we discuss future work

Calibration and Performance of the REgolith X-Ray Imaging Spectrometer (REXIS) Aboard NASA’s OSIRIS-REx Mission to Bennu

Abstract The REgolith X-ray Imaging Spectrometer (REXIS) instrument on board NASA’s OSIRIS-REx mission to the asteroid Bennu is a Class-D student collaboration experiment designed to detect fluoresced X-rays from the asteroid’s surface to measure elemental abundances. In July and November 2019 REXIS collected ∼615 hours of integrated exposure time of Bennu’s sun-illuminated surface from terminator orbits. As reported in Hoak et al. (Results from the REgolith X-ray Imaging Spectrometer (REXIS) at Bennu, 2021) the REXIS data do not contain a clear signal of X-ray fluorescence from the asteroid, in part due to the low incident solar X-ray flux during periods of observation. To support the evaluation of the upper limits on the detectable X-ray signal that may provide insights for the properties of Bennu’s regolith, we present an overview of the REXIS instrument, its operation, and details of its in-flight calibration on astrophysical X-ray sources. This calibration includes the serendipitous detection of the transient X-ray binary MAXI J0637-430 during Bennu observations, demonstrating the operational success of REXIS at the asteroid. We convey some lessons learned for future X-ray spectroscopy imaging investigations of asteroid surfaces

Thermal Effects In the Input Optics of the Enhanced Laser Interferometer Gravitational-Wave Observatory Interferometers

We present the design and performance of the LIGO Input Optics subsystem as implemented for the sixth science run of the LIGO interferometers. The Initial LIGO Input Optics experienced thermal side effects when operating with 7 W input power. We designed, built, and implemented improved versions of the Input Optics for Enhanced LIGO, an incremental upgrade to the Initial LIGO interferometers, designed to run with 30 W input power. At four times the power of Initial LIGO, the Enhanced LIGO Input Optics demonstrated improved performance including better optical isolation, less thermal drift, minimal thermal lensing, and higher optical efficiency. The success of the Input Optics design fosters confidence for its ability to perform well in Advanced LIGO

Building America Industrialized Housing Partnership (BAIHP II)

This report summarizes the work conducted by the Building America Industrialized Housing Partnership (BAIHP - www.baihp.org) during the final budget period (BP5) of our contract, January 1, 2010 to November 30, 2010. Highlights from the four previous budget periods are included for context. BAIHP is led by the Florida Solar Energy Center (FSEC) of the University of Central Florida. With over 50 Industry Partners including factory and site builders, work in BP5 was performed in six tasks areas: Building America System Research Management, Documentation and Technical Support; System Performance Evaluations; Prototype House Evaluations; Initial Community Scale Evaluations; Project Closeout, Final Review of BA Communities; and Other Research Activities