Physical Sciences and Mathematics Commons^™

Merging Neutron Star And Black Hole Binaries: Inference Of Their Parameters And Simulations Of Their Formation And Fate, Soumi De

Dissertations - ALL

In recent years, the growing numbers of black hole and neutron star merger candidates observed by the Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory) and Virgo gravitational-wave observatories are rapidly expanding the frontiers of astrophysics. The observations enable (i) direct measurements of properties of these compact objects with information extraction from the gravitational-wave data, and seek the understanding of (ii) mechanisms by which the close compact object binaries come into existence and (iii) the astrophysical processes that take place after they merge. This thesis presents work on all these three fronts (i) We present measurements of properties of the binary neutron …

Detection And Inference In Gravitational Wave Astronomy, Steven Daniel Reyes

Dissertations - ALL

We explore the detection and astrophysical modeling of gravitational waves de- tected by the Advanced Laser Interferometer Gravitational wave Observatory (LIGO) and Virgo. We discuss the techniques used in the PyCBC search pipeline to discover the first gravitational wave detection GW150914, and estimate the statistical signifi- cance of GW150914, and the marginal trigger LVT151012. During Advanced LIGO’s first observing run there were no detections of mergers from binary neutron star and neutron star-black hole binaries. We use Bayesian inference to place upper limits on the rate of coalescence of these binaries. We use developments made in the PyCBC search pipeline …

Towards Probing The Strong Field Gravity Using Binary Black-Hole Ringdowns, Swetha Bhagwat

Dissertations - ALL

In this thesis, we study black hole ringdowns as a probe to understand the strong-field clssical gravity. When two black holes merge, they form a single distorted black hole that then radiates gravitational waves and settles into a final stable Kerr state. The signal produced during this process is called the ringdown and can be modelled as perturbations on the space-time of the final Kerr black hole. Ringdowns contain information about the strong field dynamics close to the black holes and thus, can be used to test our understanding of gravity. There are three specific questions that we explore in …

Angular Trapping Of A Mirror Using Radiation Pressure, David Bruce Kelley

Dissertations - ALL

Alignment control in gravitational-wave detectors has consistently proven to be a

dicult problem due to the stringent noise contamination requirement for the gravitational

wave readout and the radiation-pressure induced angular instability in Fabry-

Perot cavities (Sidles-Sigg instability). In this thesis, I present optical springs as a

tool to damp the motion of a mirror. I discuss the design and implementation of a single

degree-of-freedom optical spring system and the importance of the photothermal

eect in properly predicting optical spring behavior.

I also present the development and implementation of an angular control scheme,

attempting to damp two degrees of freedom with …

Topics In Gravitational-Wave Astrophysics, Prayush Kumar

Dissertations - ALL

In this dissertation we study the applicability of different waveform models in

gravitational wave searches for comparable mass binary black holes. We determine

the domain of applicability of the computationally inexpensive closed form models,

and the same for the semi-analytic models that have been calibrated to Numerical

Relativity simulations (and are computationally more expensive). We further explore

the option of using hybrid waveforms, constructed by numerically stitching analytic

and numerical waveforms, as filters in gravitational wave detection searches. Beyond

matched-filtering, there is extensive processing of the filter output before a detection

candidate can be confirmed. We utilize recent results from …

Characterization Of Enhanced Interferometric Gravitational Wave Detectors And Studies Of Numeric Simulations For Compact-Binary Coalescences, Larne Pekowsky

Physics - Dissertations

Gravitational waves are a consequence of the general theory of relativity. Direct detection of such waves will provide a wealth of information about physics, astronomy, and cosmology. A worldwide effort is currently underway to make the first direct detection of gravitational waves. The global network of detectors includes the Laser Interferometer Gravitational-wave Observatory (LIGO), which recently completed its sixth science run.

A particularly promising source of gravitational waves is a binary system consisting of two neutron stars and/or black holes. As the objects orbit each other they emit gravitational radiation, lose energy, and spiral inwards. This produces a characteristic ``chirp'' …

Searching For Gravitational Waves From Compact Binary Coalescence Using Ligo And Virgo Data, Collin Capano

Physics - Dissertations

This thesis describes current efforts to search for gravitational waves from compact binary coalescences (CBCs) by the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration. We briefly review the physics of gravitational-wave emission and detection, describing how gravitational waves are emitted from "inspiraling" compact stellar mass objects and how the LSC and Virgo try to detect them using interferometers. Next we review the data-analysis principles used to search for potential signals in the detectors' noise. These principles are employed by ``ihope," which is the data-analysis pipeline used to search for CBCs. We describe each step in this pipeline and discuss …