Evolution of the Magnetic Field in Accreting Neutron Stars

TL;DR

This thesis investigates how the magnetic field in neutron stars evolves during accretion in binary systems, aiming to explain the formation of millisecond pulsars through theoretical modeling and comparison with observations.

Contribution

It introduces a comprehensive analysis of magnetic field evolution mechanisms in accreting neutron stars, including crustal flux evolution and core flux implications, linking theory with observed pulsar properties.

Findings

Diamagnetic screening affects the neutron star's magnetic field strength.

Crustal magnetic flux evolution can explain observed field decay.

Initial core flux configuration influences the magnetic field evolution and observational signatures.

Abstract

In this thesis we address the question of {\em the evolution of the magnetic field in neutron stars}. There has been sufficient observational indication suggesting a causal connection between the binary history of neutron stars and the evolution of their magnetic field. In particular, it is believed that the generation of the low-field millisecond pulsars is a consequence of the processing of normal high-field neutron stars in binary systems. Therefore, in this thesis we try to understand the mechanism of field evolution in neutron stars that are members of binary systems with an aim to understand the problem of millisecond pulsar generation. To this end we have looked at four related problems as described below : 1. the effect of diamagnetic screening on the final field of a neutron star accreting material from its binary companion; 2. evolution of magnetic flux located in the crust of an accreting neutron star; 3. application of the above-mentioned model to real systems and a comparison with observations; 4. an investigation into the consequences of magnetic flux being initially located in the core of the star and its observational implications.