Astrophysical Consequence of Strong Gravitational Field and its Observational Possibility
Project/Area Number  08640378 
Research Category 
GrantinAid for Scientific Research (C)

Section  一般 
Research Field 
素粒子・核・宇宙線

Research Institution  HIROSHIMA UNIVERSITY 
Principal Investigator 
KOJIMA Yasufumi Hiroshima University, Deaprtment of Physics Professor, 理学部, 教授 (10192577)

Project Fiscal Year 
1996 – 1998

Project Status 
Completed(Fiscal Year 1998)

Budget Amount *help 
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1998 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1997 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1996 : ¥1,000,000 (Direct Cost : ¥1,000,000)

Keywords  general relativity / neutron star / hydrodynamical stability / 一般相対論 / 中性子星 / 流体力学的安定性 / 中性子量 / 中性子線 / 相対性理論 / 重力波 / ニュートリノ 
Research Abstract 
The aim of this research project was to examine relativisticeffects, which may be in the near future observed in astrophysics. For three years supported by the grant, the following topics are examined. (1) As the binary of neutron stars shrinks due to gravitationalradiation, the postNewtonian gravitational effects to the orbital motion and the hydrodynamical effects become more important. A simplified model, in which the dynamical degrees offreedom are restricted, is adopted to evaluate the spinorbit, spinspin and tidal effects in the coalescence. (2) Quantum mechanical oscillation is calculated for neutrinospropagating in weak external gravitational field. Since the peak of wave packet is important to exhibit the oscillation, the main terms are evaluated. The correction to the result of flat spacetime is explicitly derived. The correction should however be careful for the definition of the energy and lengt etc. The interpretation of the correction is subtle since spacetimes with gravity and without gravity are distinct. (3)One of wellknown approximation used in the Newtonian pulsation theory is socalled the Cowling approximation in which gravitational perturbation is neglected. The accuracy in the relativistic slowly rotating stars is tested. The result shows the accuracy is fairly good without any change of the qualitative pictures. Axial mode oscillation is also examined in the relativity. At the lowest order of the rotation, the perturbation equation is reduced to singular eigenvalue problem. This means that higher order effects are important to determine the spatial function. Indeed, the spatial function describing the oscillation is determined by the Cowling approximation. It is found that the entropy distribution is 'crucial. For the uniform entropy distribution, the mode is restricted to some class.

Report
(5results)
Research Output
(22results)