Date of Award

August 2023

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Physics

First Advisor

David L Kaplan

Committee Members

Dawn Erb, Sarah Vigeland, Jolien Creighton, Philip Chang

Keywords

neutron star, pulsar, radio

Abstract

Pulsars provide some of the richest laboratories for studying the behavior of ultra-dense matter. As such, they have been utilized for decades to place stringent limits on gravitation and as probes of the material that fills our Galaxy. These tests benefit greatly from a catalog of pulsars that is as complete as possible, which in turn requires thorough searches of the Galaxy and precise timing of discoveries. These searches are informed by the continued characterization of the pulsar population, and so searching techniques develop in tandem with the analysis of their discoveries. Large scale pulsar surveys find pulsars; small scale follow-up on those discoveries uncover the pulsars' potential for continued science. In this way, both techniques are crucial to the future of pulsar experimentation.

In this dissertation, I discuss the continued analysis of two pulsar surveys utilizing the Green Bank Telescope and subsequent follow-up on the sources from them. In Chapter 1, I provide an overview on the behavior and evolution of pulsars. Aside from the pulsars themselves, I discuss modern pulsar searching techniques and some of the complexities inherent in pulsar timing. In Chapter 2, discussion focuses on the largest radio survey conducted to date: the Green Bank North Celestial Cap survey. This survey has discovered many pulsars that have led to seminal papers in gravitation and neutron star equations of state, but also provides an unprecedented snapshot of the pulsar population at 350 MHz. I utilize these data to assess the survey's sensitivity to pulsars, an analysis that impacts Galactic population models. In Chapter 3, I shift focus to the GBT 820 MHz Cygnus survey, which covers a much smaller region of the Galactic plane that hosts an abundance of active stellar formation. Deep scans of this dense region uncovered several new pulsars, including a source in a relativistic orbit with a massive white dwarf companion. I discuss this source and its follow-up in detail, and utilize the survey results to highlight deficiencies in Galactic models commonly used for pulsar searching. In Chapter 4, I return to the GBNCC survey, but in the context of long-term timing follow-up of its discoveries. Through the use of a pipeline developed to maintain pulsar solutions as high-cadence data are continually collected from observatories like CHIME, I have updated timing solutions for 128 pulsars. This procedure has given rise to many newly measured parameters and updates to those that were previously published; it also provides a framework for iterative pulsar timing that will be essential in the era of dedicated, regular observations of large groups of pulsars. In Chapter 5, I provide an overview of the results from these studies and briefly discuss the future in pulsar searching and timing.

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