Studies on Gravitational Waves and Stars with Neutron Cores

Author: Zimmermann, Mark Edward

Year: 1980

Degree: Dissertation (Ph.D.)

Advisor: Thorne, Kip S.

Committee Member: Unknown, Unknown

Option: Physics

DOI: 10.7907/n4hc-5489

Abstract

This thesis reports on investigations in two major areas: astrophysics and relativity. It is divided into six independent chapters.

Chapter I contains estimates of the astrophysically-likely amplitude of gravitational radiation emitted by the Crab and Vela pulsars. For my analysis, I model the pulsars as rapidly-rotating, freely-precessing, rigid or elastic solid bodies. I find that the Crab is likely to produce gravitational waves at Earth with dimensionless amplitude 10-27±2, and that Vela is likely to give waves one or two orders of magnitude larger.

Chapters II and III study the gravitational radiation produced by an idealized rotating and freely-precessing rigid body in the weak-field, slow-motion, small-stresses, quadrupole-moment formalism. Chapter II gives the results for axisymmetric objects and for arbitrarily shaped objects undergoing small-angle precession. In that chapter, I also discuss the application of my results to neutron stars in nature, and I describe in detail how to analyze the incoming waves and extract information about their source. Chapter III extends the analysis of Chapter II to the general case of an arbitrary rigid body undergoing large-angle precession.

Chapter IV considers all astrophysically-reasonable sources of gravitational waves. Based on a minimal set of "cherished beliefs" about the universe and about gravitation, I give general upper limits to the expected intensity of gravitational radiation at the earth, at various frequencies and from a variety of sources.

Chapter V examines a "natural" coordinate system which might be set up by a rotating and accelerating observer. I expand the metric through second-order terms in distance from the origin of the coordinates; from the metric, I derive the equations of motion for test particles. I identify many forces and pseudoforces in the equations of motion, and I discuss how my results may be used to analyze some laboratory gravitational experiments.

Chapter VI of this thesis is a report on my results in studying nucleo-synthesis in stars with neutron-star cores. I was not able to generate any self-consistent models with a total mass of 16 M⊙, core mass of 1 M⊙,

and core radius of 10 km; nuclear reactions fell short of producing the needed luminosity by a factor of 25 or more. I describe in detail my modeling procedures and the reasons for the failure of nucleosynthesis, and I point out extensions and modifications of my models which may be more successful.

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