Physical Sciences and Mathematics Commons^™

Characterizing And Mitigating Transient Noise In Ligo Observatories For Gravitational Wave Detection, Jane Glanzer

LSU Doctoral Dissertations

The existence of gravitational waves is predicted by Albert Einstein's Theory of General Relativity. Commonly referred to as "ripples in spacetime", these waves are generated by some of the most violent and energetic processes in the universe. Despite their theoretical prediction over a century ago, it wasn't until 2015 that the Advanced LIGO (aLIGO) interferometers in Hanford, WA and Livingston, LA directly detected gravitational waves for the first time, confirming Einstein's theory and ushering in a new era of astrophysics.

Detecting gravitational waves requires incredible precision. Because of the extreme sensitivity required, it is possible for the gravitational wave data …

Search Full Text Options Here 1 Of 1 Constraints From Ligo O3 Data On Gravitational-Wave Emission Due To R-Modes In The Glitching Pulsar Psr J0537-6910, R. Abbott, T. D. Abbott

Faculty Publications

We present a search for continuous gravitational-wave emission due to r-modes in the pulsar PSR J0537-6910 using data from the LIGO-Virgo Collaboration observing run O3. PSR J0537-6910 is a young energetic X-ray pulsar and is the most frequent glitcher known. The inter-glitch braking index of the pulsar suggests that gravitational-wave emission due to r-mode oscillations may play an important role in the spin evolution of this pulsar. Theoretical models confirm this possibility and predict emission at a level that can be probed by ground-based detectors. In order to explore this scenario, we search for r-mode emission in the epochs between …

Measurements And Mitigation Of Scattered Light Noise In Ligo, Corey Daniel Austin

LSU Doctoral Dissertations

The Advanced LIGO (aLIGO) detectors use 1064 nm lasers to measure the tiny fluctuations in spacetime that occur when gravitational waves pass through the earth. LIGO makes use of advanced coating methods and materials to limit the amount of light that scatters from the main beam, but some amount of light does scatter. This stray light can interact with surfaces inside the interferometer that are not seismically isolated and then recombine with the main beam, introducing excess noise into the gravitational wave channel. This thesis reviews the methods for modeling scattered light with ray tracing software and analytical models, for …

High Power And Optomechanics In Advanced Ligo Detectors, Terra Christine Hardwick

LSU Doctoral Dissertations

In September 2015, a new era of astronomy began with the first direct detection of grav- itational waves from a binary black hole coalescence. The event was captured by the Laser Interferometer Gravitational-wave Observatory, comprised of two long-baseline interferometers, one in Livingston, LA and one in Hanford, WA. At the time of the first detection, the interferometers were part way through an upgrade to an advanced configuration and were operating with a strain sensitivity of just better than 10⁻²³/Hz^1/2 around 100Hz. The full Advanced LIGO design calls for sensitivity of a few parts in 10⁻²⁴/Hz …

Broadband Measurement And Reduction Of Quantum Radiation Pressure Noise In The Audio Band, Jonathan Daniel Cripe

LSU Doctoral Dissertations

One hundred years after Albert Einstein predicted the existence of gravitational waves in his general theory of relativity, the Laser Interferometer Gravitational-Wave Observatory (LIGO) made the first direct detection of gravitational waves. Since the first detection of gravitational waves from a binary black hole merger, LIGO has gone on to detect gravitational waves from multiple binary black hole mergers, and more recently from a binary neutron star merger in collaboration with telescopes around the world. The detection of gravitational waves has opened a new window to the universe and has launched the era of gravitational wave astronomy.

With the first …

The Effects Of Instrumental Noise On Searches For Generic Transient Gravitational Waves In Advanced Ligo, Marissa Walker

LSU Doctoral Dissertations

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 …

Performance Characterization Of The Dual-Recycled Michelson Subsystem In Advanced Ligo, Anamaria Effler

LSU Doctoral Dissertations

General relativity predicts the existence of gravitational waves as ripples in spacetime propagating at the speed of light. They couple to matter weakly, which implies only cataclysmic cosmic events generating such waves can be detected. Binary neutron star coalescences are, for example, one of the most promising detectable source. Their weak coupling also implies that very sensitive instruments are needed to detect them, and the most sensitive so far have been laser interferometers with km-scale arms. The Laser Interferometric Gravitational wave Observatory (LIGO) is exactly such an instrument, and the most sensitive in the world to the date of this …

Searches For Gravitational Waves From Perturbed Black Holes In Data From Ligo Detectors, Sarah Elizabeth Caudill

LSU Doctoral Dissertations

Black hole perturbation theory predicts that a perturbed black hole will emit gravitational waves in a superposition of quasi-normal modes. Various astrophysical processes can produce such a black hole including the merger of two compact binary neutron stars or black holes. The final form of the waveform from such a system is known as a ringdown. We discuss the search through data from LIGO's fifth science run for ringdown gravitational waves from intermediate mass black holes using a matched filtering pipeline. We outline the improvements to the pipeline since LIGO's fourth science run including the creation of a fully automated …

Homodyne Detection For Laser-Interferometric Gravitational Wave Detectors, Tobin Thomas Fricke

LSU Doctoral Dissertations

Gravitational waves are ripples of space-time predicted by Einstein's theory of General Relativity. The Laser Interferometer Gravitational-wave Observatory (LIGO), part of a global network of gravitational wave detectors, seeks to detect these waves and study their sources. The LIGO detectors were upgraded in 2008 with the dual goals of increasing the sensitivity (and likelihood of detection) and proving techniques for Advanced LIGO, a major upgrade currently underway. As part of this upgrade, the signal extraction technique was changed from a heterodyne scheme to a form of homodyne detection called DC readout. The DC readout system includes a new optical filter …

Generalized Curvilinear Advection Formalism For Finite Volume Codes Doing Relativistic Hydrodynamics, Jay Michael Call

LSU Doctoral Dissertations

While it is possible to numerically evolve the relativistic fluid equations using any chosen coordinate mesh, typically there are distinct computational advantages associated with different types of candidate grids. For example, astrophysical flows that are governed by rotation tend to give rise to advection variables that are naturally conserved when a cylindrical mesh is used. On the other hand, Cartesian-like coordinates afford a more straightforward implementation of adaptive mesh refinement (AMR) and avoid the appearance of coordinate singularities. Here it is shown that it should be possible to reap the benefits associated with multiple types of coordinate systems simultaneously in …

Modeling Thermal Phenomena And Searching For New Thermally Induced Monitor Signals In Large Sale Gravitational Wave Detectors, Rupal Shashikant Amin

LSU Doctoral Dissertations

The Laser Interferometer Gravitational-wave Observatory (LIGO) array’s 4 km detectors have transitioned from an initial configuration (iLIGO) to an enhanced configuration (eLIGO) [1]. Both configurations relied on high circulating laser powers to achieve sensitivity goals between 150 Hz and 8 kHz. These power levels were sufficient to induce thermally driven focal affects in the primary optics. Since the detectors were designed to achieve maximum sensitivity when laser light was optimally coupled (mode matched) into the antenna, small deviations in focal parameters influenced performance. A laser based thermal compensation system (TCS) was installed for use in both configurations to counteract excessive …

Matter Sources Interacting With A Black Hole: Dynamics And Observable Signatures, Miguel Megevand

LSU Doctoral Dissertations

Dynamical systems involving black holes are one of the most promising sources of detectable gravitational waves. Additionally, one expects strong electromagnetic signals whenever matter sources are present. In this dissertation, we study different astrophysical scenarios pertaining the interaction of matter with a black hole. We first investigate the possibility to localize scalar field configurations surrounding a (dynamic) black hole. The analytical study is illustrated by performing numerical simulations that show the evolution of a Klein-Gordon-like scalar field shell surrounding a black hole. Second, we present a method to estimate the gravitational wave frequency at the end of the inspiral phase …

Mass Transfer And Evolution Of Compact Binary Stars, Vayujeet Gokhale

LSU Doctoral Dissertations

We present a study of key aspects of the evolution of binary stars with emphasis on binaries consisting of two white dwarf stars. The evolution of such systems is driven by the loss of angular momentum by gravitational wave radiation. Effects like mass transfer and other modes of angular momentum loss and redistribution influence the evolutionary fate of the binary, and can lead to a merger, the tidal disruption of one of the components or its survival as a long-lived AM Canum Venaticorum (AM CVn) type system. Our study takes into account some of these effects; like mass loss, tides, …

Gravitational Radiation Detectability Of Supernova 1987a'S Remnant Fully Matched Filter For Double Resonant Gravitational Detector, Giovanni Santostasi

LSU Doctoral Dissertations

Part I There is some observational evidence of the presence of a pulsating light source in the remnant of the supernova (SN) 1987A [1]. This source is considered to be a rotating neutron star. Fourier analysis of the light intensity of this source reveals a main narrow frequency peak and side bands that are understood as a modulation of the main sinusoidal signal. A particular model of the neutron star invokes a precessing object to explain the modulation. From the Fourier spectrum of the source and changes in the frequency value, we can determine important parameters of the spinning neutron …