National Technical Reports Library

The National Technical Information Service acquires, indexes, abstracts, and archives the largest collection of U.S. government-sponsored technical reports in existence. The NTRL offers online, free and open access to these authenticated government technical reports. Technical reports and documents in its repository may be available online for free either from the issuing federal agency, the U.S. Government Publishing Office’s Federal Digital System website, or through search engines.

Details

Resonant Excitation of White Dwarf Oscillations in Compact Object Binaries: 1. The No Back Reaction Approximation.

DE2004826967

Publication Date	2004
Personal Author	Rathore, Y.; Blandford, R. D.
Page Count	20
Abstract	We consider the evolution of white dwarfs with compact object companions (specifically black holes with masses up to (approx) 10(sup 6) M(sub (circle-dot)), neutron stars, and other white dwarfs). We suppose that the orbits are initially quite elliptical and then shrink and circularize under the action of gravitational radiation. During this evolution, the white dwarfs will pass through resonances when harmonics of the orbital frequency match the stellar oscillation eigenfrequencies. As a star passes through these resonances, the associated modes will be excited and can be driven to amplitudes that are so large that there is a back reaction on the orbit which, in turn, limits the growth of the modes. A formalism is presented for describing this dynamical interaction for a non-rotating star in the linear approximation when the orbit can be treated as non-relativistic. A semi-analytical expression is found for computing the resonant energy transfer as a function of stellar and orbital parameters for the regime where back reaction may be neglected. This is used to calculate the results of passage through a sequence of resonances for several hypothetical systems. It is found that the amplitude of the (ell) = m = 2 f-mode can be driven into the non-linear regime for appropriate initial conditions. We also discuss where the no back reaction approximation is expected to fail, and the qualitative effects of back reaction.
Keywords	White dwarf stars Oscillations Black holes (Astronomy) Binary stars Galaxies Neutron stars Stellar orbits Eigenfrequency Formalism Interaction Mathematical models Equations White Dwarf Compact Object (WDCO) systems
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Caltech, Pasadena, CA. Theoretical Astrophysics Dept.; Department of Energy, Washington, DC.; Stanford Univ., CA. Kavli Institute for Particle Astrophysics and
Supplemental Notes	Prepared in cooperation with Stanford Univ., CA. Kavli Institute for Particle Astrophysics and Cosmology. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200508

Resonant Excitation of White Dwarf Oscillations in Compact Object Binaries: 1. The No Back Reaction Approximation.

Resonant Excitation of White Dwarf Oscillations in Compact Object Binaries: 1. The No Back Reaction Approximation.
DE2004826967

Publication Date	2004
Personal Author	Rathore, Y.; Blandford, R. D.
Page Count	20
Abstract	We consider the evolution of white dwarfs with compact object companions (specifically black holes with masses up to (approx) 10(sup 6) M(sub (circle-dot)), neutron stars, and other white dwarfs). We suppose that the orbits are initially quite elliptical and then shrink and circularize under the action of gravitational radiation. During this evolution, the white dwarfs will pass through resonances when harmonics of the orbital frequency match the stellar oscillation eigenfrequencies. As a star passes through these resonances, the associated modes will be excited and can be driven to amplitudes that are so large that there is a back reaction on the orbit which, in turn, limits the growth of the modes. A formalism is presented for describing this dynamical interaction for a non-rotating star in the linear approximation when the orbit can be treated as non-relativistic. A semi-analytical expression is found for computing the resonant energy transfer as a function of stellar and orbital parameters for the regime where back reaction may be neglected. This is used to calculate the results of passage through a sequence of resonances for several hypothetical systems. It is found that the amplitude of the (ell) = m = 2 f-mode can be driven into the non-linear regime for appropriate initial conditions. We also discuss where the no back reaction approximation is expected to fail, and the qualitative effects of back reaction.
Keywords	White dwarf stars Oscillations Black holes (Astronomy) Binary stars Galaxies Neutron stars Stellar orbits Eigenfrequency Formalism Interaction Mathematical models Equations White Dwarf Compact Object (WDCO) systems
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Caltech, Pasadena, CA. Theoretical Astrophysics Dept.; Department of Energy, Washington, DC.; Stanford Univ., CA. Kavli Institute for Particle Astrophysics and
Supplemental Notes	Prepared in cooperation with Stanford Univ., CA. Kavli Institute for Particle Astrophysics and Cosmology. Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200508