Abstract

Recent studies have shown that orbital eccentricity may serve as an important indicator of dynamical assembly as a formation channel for binary black holes. In contrast to binaries that evolve in isolation and circularize through long-term gravitational radiation, dynamically assembled binaries, such as those formed through gravitational encounters in dense stellar environments, may retain measurable eccentricity up to the point of merger. Because eccentricity leaves a distinct imprint on gravitational-wave signals, it provides a powerful observational handle on the astrophysical origins of compact binaries. Detecting this signature requires sensitive and accurate modeling of gravitational-wave signals, particularly as binaries enter the LIGO frequency band where most circular systems dominate. Although no confident detection of eccentricity has yet been made, the increasing sensitivity of the current detector network (LIGO, Virgo, and KAGRA) and the growing number of observed events make the prospect of identifying eccentric mergers increasingly promising. In this work, I investigate multiple approaches to quantifying and characterizing orbital eccentricity in binary black hole mergers. I begin by evaluating the effectiveness of the RIFT (Rapid Inference via Iterative FiTting) parameter estimation pipeline in recovering eccentric signals. I describe several improvements made to the RIFT framework to better handle the complex waveform morphologies introduced by eccentricity, including modifications to the likelihood evaluation and sampling strategies. In parallel, I develop and explore direct, waveform-based methods for estimating eccentricity from the asymptotic gravitational-wave signal itself, without requiring a full parameter estimation analysis. These methods provide a complementary and computationally efficient path toward identifying eccentric systems in large datasets. Beyond these core investigations, I also describe contributions to several collaborative and community-driven efforts within the field. These include integrating eccentric numerical relativity (NR) waveforms directly into RIFT analyses to validate parameter recovery, performing eccentric parameter estimation for both individual event studies and population-level analyses, and contributing to the development of an effective-one-body (EOB) waveform model that incorporates both eccentricity and spin precession. Collectively, these efforts aim to advance our ability to detect, interpret, and model eccentric binary black hole mergers, paving the way for a more complete understanding of the diverse dynamical processes that shape compact binary populations in the Universe.

Library of Congress Subject Headings

Stellar mergers; Black holes (Astronomy); Double stars; Gravitational waves--Measurement

Publication Date

10-2025

Document Type

Dissertation

Student Type

Graduate

Degree Name

Astrophysical Sciences and Technology (Ph.D.)

Department, Program, or Center

Physics and Astronomy, School of

College

College of Science

Advisor

Richard O'Shaughnessy

Advisor/Committee Member

Edwin Hach

Advisor/Committee Member

Carlos Lousto

Campus

RIT – Main Campus

Plan Codes

ASTP-PHD

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