by Lin Lap-Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves [105]-109). / Text in English; abstracts in English and Chinese. / by Lin Lap-Ming. / Abstract --- p.i / Acknowledgement --- p.ii / Contents --- p.iii / List of Figures --- p.vi / List of Tables --- p.ix / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Physical Motivation --- p.1 / Chapter 1.2 --- Quasi-Normal Modes --- p.3 / Chapter 1.3 --- Superfluidity in Neutron Stars --- p.7 / Chapter 1.4 --- Outline of this Thesis --- p.9 / Chapter Chapter 2. --- The Ordinary Perfect Fluid Neutron Stars --- p.11 / Chapter 2.1 --- The Equilibrium Neutron Star Models --- p.11 / Chapter 2.2 --- Non-Radial Oscillations of Neutron Stars --- p.14 / Chapter 2.3 --- The Quasi-Normal Modes of Stars --- p.17 / Chapter 2.3.1 --- The Fluid Modes --- p.17 / Chapter 2.3.2 --- The Spacetime Modes --- p.18 / Chapter Chapter 3. --- The General Relativistic Superfluid Formalism --- p.22 / Chapter 3.1 --- The Carter Formalism --- p.22 / Chapter 3.2 --- The Master Function --- p.25 / Chapter Chapter 4. --- The Equilibrium Superfluid Neutron Stars --- p.27 / Chapter 4.1 --- The Equilibrium Configurations --- p.27 / Chapter 4.2 --- Initial and Boundary Conditions --- p.34 / Chapter 4.3 --- Polytropic Models --- p.36 / Chapter Chapter 5. --- Non-Radial Oscillations of Superfluid Neutron Stars --- p.40 / Chapter 5.1 --- The Linearized Field Equations Inside the Star --- p.40 / Chapter 5.1.1 --- Equations for Even-Parity Perturbations --- p.45 / Chapter 5.1.2 --- Equations for Odd-Parity Perturbations --- p.48 / Chapter 5.2 --- Initial and Boundary Conditions --- p.49 / Chapter 5.2.1 --- Radial Integration Initial Conditions --- p.49 / Chapter 5.2.2 --- Boundary conditions at the Surface --- p.55 / Chapter 5.3 --- The Linearized Field Equations Outside the Star --- p.57 / Chapter 5.4 --- Numerical Technique --- p.60 / Chapter Chapter 6. --- Quasi-Normal Modes Extraction --- p.62 / Chapter 6.1 --- Numerical Techniques for Quasi-Normal Modes Extraction --- p.62 / Chapter 6.2 --- The Leaver Series --- p.64 / Chapter 6.3 --- The Graphical Method --- p.67 / Chapter Chapter 7. --- The Quasi-Normal Modes of Superfluid Neutron Stars --- p.69 / Chapter 7.1 --- Polytropic Models --- p.69 / Chapter 7.1.1 --- The w-modes --- p.70 / Chapter 7.1.2 --- The f- and p-modes --- p.74 / Chapter 7.2 --- Ideal Neutron-Proton-Electron Gas --- p.82 / Chapter 7.3 --- Convergence Tests and Accuracy --- p.92 / Chapter Chapter 8. --- Conclusion --- p.95 / Appendix A. Speeds of Sound --- p.97 / Appendix B. Equations for Radial Oscillations --- p.99 / Appendix C. Numerical Technique for Solving Leaver's Series --- p.101 / Appendix D. Scaling in Numerical Calculations --- p.103 / Bibliography --- p.105

Neutron stars are surrounded by dense magnetospheres with nontrivial magnetic field structure. They are sources of multi-band emission from radio waves to very high energy gamma-rays. Pulsar wind nebulae observations also show that a large number of e^± pairs flow from the neutron star, which are produced in the magnetosphere. The structure of the magnetosphere, the mechanism of pair production and particle acceleration in the magnetosphere, and how magnetic energy is converted to kinetic energy is a complex problem that only recently has started to be addressed fully from first principles. In this dissertation I describe how I developed a numerical code tailored to study this problem. A detailed description of the code and method is given, then it is used to study the pair discharge mechanism in the magnetosphere of rotating neutron stars whose rotating axis is aligned with the magnetic axis. It was found that to form the an active magnetosphere it is necessary to have pair creation all the way towards the light cylinder. In the dissertation I classify the pulsars into two classes, and describe their differences. The magnetospheres of magnetars are believed to be different from ordinary pulsars, in that they are sustained not by the rotation of the star, but by a twist launched from the stellar surface due to some sudden breakdown of the crust. I apply the same numerical tool to study the particle acceleration and pair creation mechanism in the twisted magnetosphere of the magnetar, showing where the gap is, and how the magnetosphere evolves over time. The magnetic twist was found to live much longer than the Alfvén time of the system, and slowly dissipates through developing a cavity in the inner magnetosphere. This not only explains the long term evolution of the magnetar lightcurve after an outburst, but also explains the observed evolution hotspots on the stellar surface.

Wong, Ka Sin Jamie = 超流性對中子星振盪的影響 / 黃家倩. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 212-215). / Abstract also in Chinese. / Wong, Ka Sin Jamie = Chao liu xing dui zhong zi xing zhen dang de ying xiang / Huang Jiaqian. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivations --- p.1 / Chapter 1.2 --- Outline of Thesis --- p.3 / Chapter 1.3 --- Notation and Conventions --- p.4 / Chapter 2 --- The Relativistic Superfluid Star --- p.7 / Chapter 2.1 --- The Carter Formalism --- p.7 / Chapter 2.2 --- The Equilibrium Superfluid Star Models --- p.9 / Chapter 2.3 --- Non-Radial Oscillations of Superfluid Neutron Star --- p.13 / Chapter 2.3.1 --- Equations for Even-Parity Perturbations --- p.16 / Chapter 2.3.2 --- Equations for Odd-Parity Perturbations --- p.18 / Chapter 2.3.3 --- Linearised Equations Outside the Star --- p.19 / Chapter 2.3.4 --- Boundary Conditions for Quasinormal Modes --- p.21 / Chapter 2.3.5 --- Quasinormal Mode Spectrum of Superfluid Stars --- p.22 / Chapter 3 --- Universality in Superfluidf-mode --- p.25 / Chapter 3.1 --- What is an f-mode? --- p.25 / Chapter 3.2 --- Uncoupled Polytropic Master Function for Superfluid Stars --- p.27 / Chapter 3.3 --- Reparametrising the Uncoupled Polytropic Master Function --- p.29 / Chapter 3.4 --- f-mode Frequency of Uncoupled Polytropic Superfluid Stars --- p.30 / Chapter 3.5 --- "Derivation of Superfluid Mode Frequency for a Newtonian Sphere of Two Homogeneous, Incompressible, Uncoupled Fluids" --- p.40 / Chapter 4 --- Effects of Entrainment on Superfluid Mode Frequencies --- p.45 / Chapter 4.1 --- What is entrainment? --- p.45 / Chapter 4.2 --- Numerical Results --- p.48 / Chapter 4.3 --- Newtonian Variational Formalism --- p.51 / Chapter 4.4 --- Deriving the Approximate First Order Shift --- p.54 / Chapter 5 --- Variational Principle for Polar Modes --- p.60 / Chapter 5.1 --- Alternative Set of Perturbed Equations for Superfluid Neutron Star --- p.60 / Chapter 5.2 --- Boundary Conditions for Polar Quasinormal Modes --- p.64 / Chapter 5.3 --- Deriving the Variational Principle --- p.65 / Chapter 5.4 --- Recasting the Principle in Abstract Notation --- p.67 / Chapter 5.5 --- Doing Away with the Constraint Equations --- p.70 / Chapter 5.6 --- Regarding the Purely Real Nature of the First Order Term --- p.71 / Chapter 5.7 --- First Order Shift in Mode Frequency due to Entrainment --- p.74 / Chapter 6 --- Excitation of Quasinormal Modes --- p.77 / Chapter 6.1 --- Perturbed Equations Inside the Star --- p.77 / Chapter 6.2 --- Perturbed Equations Outside the Star --- p.78 / Chapter 6.3 --- Circular Orbits in Schwarzschild Spacetime --- p.80 / Chapter 6.4 --- Calculation of Source Term --- p.82 / Chapter 6.5 --- Determination of Amplitude --- p.85 / Chapter 6.6 --- Numerical Procedures --- p.86 / Chapter 6.7 --- Numerical Results --- p.89 / Chapter 7 --- Stability of Non-rotating Newtonian Superfluid Stars to Non-radial Oscillations --- p.91 / Chapter 7.1 --- Introduction --- p.91 / Chapter 7.2 --- Two-fluid Systems --- p.93 / Chapter 7.3 --- A Review of Basic Thermodynamics --- p.96 / Chapter 7.4 --- Perturbed System of Equations --- p.100 / Chapter 7.5 --- Schwarzschild Discriminant --- p.102 / Chapter 7.6 --- Variational Principle for Mode Frequency --- p.105 / Chapter 7.7 --- Stability of Polar Oscillations --- p.108 / Chapter 7.7.1 --- A Sufficient Condition for Stability --- p.109 / Chapter 7.7.2 --- A Necessary and Sufficient Condition for the Occurrence of Zero-frequency Modes --- p.112 / Chapter 7.7.3 --- Conditions for Instability --- p.119 / Chapter 7.8 --- A Little Application to Zero-temperature Superfluid Star --- p.121 / Chapter 7.9 --- Inclusion of Non-dissipative Magnus-typed Force --- p.122 / Chapter 7.10 --- Conclusion --- p.123 / Chapter 8 --- A Single Scalar Governing Stability of Newtonian Superfluid Neutron Stars to Non-radial Oscillations --- p.125 / Chapter 8.1 --- Introduction --- p.125 / Chapter 8.2 --- Summary of Results of the Last Chapter --- p.126 / Chapter 8.3 --- Motivation --- p.129 / Chapter 8.4 --- Occurrence of Neutral Modes --- p.131 / Chapter 8.5 --- S> 0 Implies Stability to Non-radial Oscillations --- p.133 / Chapter 8.6 --- S < 0 On a Finite Interval of r Implies Instability --- p.135 / Chapter 8.7 --- Conclusion --- p.137 / Chapter 9 --- Lagrangian Perturbation Theory for Rotating Non-relativistic Superfluid Stars --- p.138 / Chapter 9.1 --- Perturbation Operators --- p.139 / Chapter 9.2 --- Perturbing the Dynamical Equations --- p.143 / Chapter 9.3 --- Variational Principle and Symplectic Structure --- p.147 / Chapter 9.4 --- Showing Antisymmetry of B --- p.149 / Chapter 9.5 --- Showing Symmetry of C --- p.154 / Chapter 9.6 --- Canonical Displacement --- p.157 / Chapter 9.7 --- Using Canonical Energy in Stability Calculation --- p.163 / Chapter 9.8 --- Instability of r-mode for a Superfluid Star --- p.164 / Chapter 9.9 --- CFS Instability of Normal Modes --- p.169 / Chapter 10 --- Conclusion --- p.172 / Chapter A --- Some Useful Relations --- p.174 / Chapter B --- Derivation of Equations Given in Section 5.1 --- p.176 / Chapter C --- Order Analysis of Quantities at Stellar Radius --- p.179 / Chapter D --- Condition for the Occurrence of Non-radiating Modes --- p.182 / Chapter E --- Perturbed Equations for Polar Oscillations and Boundary Conditions --- p.186 / Chapter F --- Deriving the Variational Principle --- p.191 / Chapter G --- Discerning Similarity with Ordinary-fluid Variational Expression --- p.195 / Chapter G.l --- T'=0 --- p.195 / Chapter G.2 --- T'=0 --- p.199 / Chapter H --- A Condition for Instability of a Dynamical System --- p.202 / Chapter I --- Derivation of Zeroth-order r-mode Frequency --- p.205 / Chapter J --- Spin-s Spherical Harmonics --- p.207 / Chapter J.1 --- Spin-s Quantities --- p.207 / Chapter J.2 --- Motivation of Spin-s Spherical Harmonics --- p.208 / Chapter J.3 --- Proof of a Relation --- p.210 / Bibliography --- p.212

No description available.

The Best M.Phil Thesis in the Faculties of Dentistry, Engineering, Medicine and Science (University of Hong Kong), Li Ka Shing Prize,1993-1995 / published_or_final_version / Physics / Master / Master of Philosophy

Hyperflares from Soft Gamma Repeaters have revealed quasi-periodic oscillations, suggested to be torsional modes of the neutron star crust produced during starquakes. We study how a magnetic field affects these modes. We make a plane-parallel model of the neutron star crust with a vertical and non-vertical field and solve for the eigenvalues and eigenfunctions. In the vertical field case we find a discrete set of modes comparable to the observed frequencies giving evidence for this theory. We find that the lower order modes do not depend on B while the higher order modes do when the field strength is low or extremely high. We make a simple analytic model of a non-vertical field in a closed box representing the neutron star crust. The mode spectrum in this model is continuous rather than discrete, raising the puzzle of why only specific modes are excited during the hyperflare.

Neutron stars in mass-transferring binaries accrete hydrogen and helium rich matter from their companions. Unstable nuclear burning of this matter results in Type I X-ray bursts every few hours to days. Theoretical models propose three regimes of unstable burning on neutron star surfaces and also define the critical accretion rate above which the neutron star burns fuel stably without bursting. Currently, the theoretical value for this stability boundary is comparable to the Eddington limit whereas the observational limit is estimated to 0.3 m&dot;Edd. In this dissertation, we examine the boundary between stable and unstable thermonuclear burning at the surface of an accreting neutron star for a range of initial compositions. We compute different steady-state equilibrium models and use them to conduct a linear perturbation analysis. The main results of this analysis are plots of the critical accretion rates as a function of the initial helium mass fraction which were never produced before.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 55-58) Also available in print.

Thesis (Ph.D.). / Written for the Dept. of Physics. Title from title page of PDF (viewed 2008/05/09). Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves [83]-90).