Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Physics and Astronomy

First Advisor

Joel E. Tohline


Magnetized neutron stars provide the basic model for radio pulsars. They also play a fundamental role in the theory of pulsating X-ray sources and explaining the origin of millisecond radio pulsars. In an effort to better understand these interesting and fundamentally important astrophysical systems, this dissertation studies the magnetic evolution of neutron stars with a dipole field supported in the crust. We explore their evolution both as isolated systems and as accreting objects in binary systems. We investigate how the incorporation of the gravitational field of the neutron star core into the spacetime occupied by a dipole field in the crust affects the behavior of the magnetic evolution of these systems and identify the factors which compete for determination of the field's decay rate over long timescales. From this we are able to characterize the magnetic field decay over a wide range of neutron star masses approaching maximum mass limits. We demonstrate that more compact stars and stars near maximum mass limits do not necessarily possess the slowest decays, as had been speculated from earlier investigations. As an extension of this work, we discuss the implications our results have on attempts to use the characteristics of the observed pulsar population to constrain the properties of magnetized neutron stars and high density matter. In our investigation of accreting, magnetized neutron stars, the accretion heating, thermomagnetic field drift, and advection of the field into deeper layers of the star are modeled simultaneously, complementing previous work and serving to complete the basic model for accretion-driven magnetic field evolution. We identify the mass transfer rates that significantly alter the character of the neutron star magnetic field. Our results further underscore the significant role played by the cooling properties of the neutron star core in determining the evolution of the field during mass transfer. Additionally, we identify the circumstances under which a strong, pre-accretion field can be preserved by transport into deep regions of the star, then resurface within a Hubble time ($\sim$10$\sp{10}$ years), dramatically altering the observable properties of the post-accretion star.