Binary Black Hole Astrophysics with Gravitational Waves
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Date
2024-01-09
Authors
Edelman, Bruce
Journal Title
Journal ISSN
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Publisher
University of Oregon
Abstract
Gravitational Waves (GWs) have quickly emerged as powerful, indispensabletools for studying gravity in the strong field regime and high-energy astrophysical
phenomena since they were first directly detected by the Laser Interferometer
Gravitational-Wave Observatory (LIGO) on September 14, 2015. Over the course
of this dissertation work gravitational-wave astronomy has begun to mature, going
from 11 GW observations when I began to 90 at the time of writing, just before
the next observing run begins. As the network of GW observatories continues to
grow and these observations become a regular occurrence, the entire population of
merging compact objects observed with GWs will provide a unique probe of the
astrophysics of their formation and evolution along with the cosmic expansion of
the universe. In this dissertation I present four studies that I have led using GWs
to better understand the astrophysics of the currently most detected GW source,
binary black holes (BBHs). We first present a novel data-driven technique to look for deviations from modeled gravitational waveforms in the data, coherent across
the network of observatories, along with an analysis of the first gravitational-
wave transient catalog (GWTC-1). The following three studies present the three
different approaches to modeling populations of BBHs, using parametric, semi-
parametric and non-parametric models. The first of these studies uses a parametric
model that imposes a gap in the mass distribution of black holes, looking for
evidence of effects caused by pair-instability supernovae. The second study
introduces a semi-parametric model that aims to take advantage of the benefits of
both parametric and non-parametric methods, by imposing a flexible perturbation
to an underlying simpler parametric description. This study was among the first
data-driven studies revealing possible structure in the mass distribution of BBHs
using GWTC-2, namely an additional peak at 10M⊙ . The final study introduces
a novel non-parametric model for hierarchically inferring population properties of
GW sources, and performs the most comprehensive data-driven study of the BBH
population to date. This study is also the first that uses non-parametric models
to simultaneously infer the distributions of BBH masses, spins and redshifts. This
dissertation contains previously published and unpublished material.
Description
Keywords
Bayesian Statistics, Black Holes, Gravitational Waves