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Type of Document Dissertation Author Haywood, Joe Reese URN etd-07102006-160546 Title Numerical Relativistic Hydrodynamic Simulations of Neutron Stars Degree Doctor of Philosophy Department Physics Advisory Committee
Advisor Name Title Grant J. Mathews Committee Chair Keywords
- binary neutron stars
- relativistic hydrodynamics
Date of Defense 2006-07-05 Availability restricted Abstract Developments in numerical relativistic hydrodynamics over the past thirtyyears, along with the advent of high speed computers, have made problems needing
general relativity and relativistic hydrodynamics tractable. One such problem
is the relativistic evolution of neutron stars, either in a head on collision or in
binary orbit. Also of current interest is the detection of gravitational radiation
from binary neutron stars, black-hole neutron star binaries, binary black holes,
etc. Such systems expected to emit gravitational radiation with amplitude large
enough to be detected on Earth by such groups as LIGO and VIRGO. Unfortunately,
the expected signal strength is below the current noise level. However,
signal processing techniques have been developed which should eventually find a
signal, if a good theoretical template can be found. In the cases above it is not
possible to obtain an analytic solution to the Einstein equations and a numerical
approximation is therefore most necessary. In this thesis the Einstein equations
are written using the formalism of Arnowitt, Desser and Misner and a conformally
flat metric is assumed. Numerical simulations of colliding neutron stars, having
either a realistic or Gamma = 2 polytropic equation of state (EOS), are presented which
confirm the rise in central density seen by [51, 89] for the softer EOS. For the binary calculation, the results of Wilson et al. [89] are confirmed, which show that
the neutron stars can collapse to black holes before colliding when the EOS is realistic
and we also confirm results of Miller [56] and others that there is essentially
no compression, the central density does not increase, when the stiffer equation of
state is used. Finally, a template for the gravitational radiation emitted from the
binary is calculated and we show that the frequency of the emitted gravitational
waves changes more slowly for the [89] EOS, which may result in a stronger signal
in the 50-100 Hz band of LIGO.
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