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https://hdl.handle.net/2142/70619
Description
Title
Neutrino Transport in Young Neutron Stars
Author(s)
Goodwin, Bruce Theron
Issue Date
1982
Department of Study
Aeronautical and Astronautical Engineering
Discipline
Aeronautical and Astronautical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Astronomy and Astrophysics
Abstract
In Part one of this thesis, I calculate the transport coefficients of degenerate neutrinos in dense matter taking into account both absorption and scattering of neutrinos by nucleons. Exact solutions of the transport equation are used, and the effect of neutron - proton interactions on the composition of the matter is allowed for. I consider energy dissipation by neutrinos and show that under many circumstances diffusion of neutrinos is more important than neutrino viscosity or heat conduction.
In Part two, I use the results of Part one to numerically solve the nonlinear diffusion equation which describes the loss of neutrinos from the inner core of a newly formed neutron star. I find that the time for the neutrinos to escape cannot be less than about one second. This time is primarily determined by the transport processes in the core and is insensitive to the boundary condition. I calculate energy dissipation due to neutrino loss and find that the total amount of dissipation is rather insensitive to the diffusion coefficient. Maximum dissipation occurs in the outer regions of the core where the diffusion coefficient is the largest and the heat capacity is the lowest. The temperature increase is modest and so not sufficient to significantly increase the pressure. I conclude that the loss times are too long for neutrino escape to be dynamically useful in matter ejection processes which occur on millisecond time scales. The loss of these neutrinos can therefore be neglected in determining the dynamical processes of neutron star formation and supernovae.
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