Dynamics of primordial phase transitions, primordial magnetic fields, and Big Bang nucleosynthesis
Cheng, Baolian
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https://hdl.handle.net/2142/22315
Description
Title
Dynamics of primordial phase transitions, primordial magnetic fields, and Big Bang nucleosynthesis
Author(s)
Cheng, Baolian
Issue Date
1993
Doctoral Committee Chair(s)
Truran, James W.
Schramm, David N.
Department of Study
Astronomy
Discipline
Astronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Astronomy and Astrophysics
Language
eng
Abstract
In this thesis, I have studied the dynamics of the inflationary universe and the possible cosmological consequences of a series of phase transitions which the universe may have undergone. Specially, I have studied the dynamics of primordial phase transitions, primordial magnetic fields, and Big Bang Nucleosynthesis. In particular, (1) I have derived the effects of magnetic fields on nucleon and particle reaction rates of astrophysical significance. The sensitivity to the presence of arbitrary degeneracy and polarization has also been examined. (2) I have calculated the effects of magnetic fields on Big Bang Nucleosynthesis and explored the impacts on the abundances of the light elements numerically. An upper limit on the strength and coherence scale of primordial magnetic fields compatible with observations of light element abundances has been placed. (3) I have proposed a new mechanism by which a magnetic field of magnitude $10\sp6$ gauss is generated on scales of 44m at the quark-hadron phase transition. The possibility of further enhancements due to dynamo action and of the astrophysical applications are discussed. (4) I have explored the dynamics of a general first order phase transition. A covariant jump condition across a bubble wall, including surface tension and dissipation, for a nongravitational moving surface, has been derived. Specially, the cosmological quark-hadron phase transition has been examined as a specific application of the general formalism, and the possible mechanism of energy transport during the phase transition is studied. (5) I have examined the role of bulk viscosity in the inflationary universe during the GUT phase transition and its effects on cosmological inflation, density fluctuations, and entropy production. Finally, I have investigated the role of gravitation in an inflationary universe and the possible relationship between gravity and inflation. The initial condition and the identification of inflation problems are probed in the framework of scalar-tensor theories of gravity. An extended inflationary cosmological model has been proposed.
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