Evolution of neutron stars with toroidal magnetic fields: Axisymmetric simulation in full general relativity

Journal Article · Tue Jul 15 00:00:00 EDT 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.78.024029· OSTI ID:21250379

Kiuchi, Kenta ^[1]; Shibata, Masaru ^[2]; Yoshida, Shijun ^[3]

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1. Department of Physics, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan)
2. Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro, Tokyo 153-8902 (Japan)
3. Astronomical Institute, Tohoku University, Sendai 980-8578 (Japan)

We study the stability of neutron stars with toroidal magnetic fields by magnetohydrodynamic simulation in full general relativity under the assumption of axial symmetry. Nonrotating and rigidly rotating neutron stars are prepared for a variety of magnetic field configuration. For modeling the neutron stars, the polytropic equation of state with the adiabatic index {gamma}=2 is used for simplicity. It is found that nonrotating neutron stars are dynamically unstable for the case where toroidal magnetic field strength varies {proportional_to} {omega}-bar{sup 2k-1} with k{>=}2 (here {omega}-bar is the cylindrical radius), whereas for k=1 the neutron stars are stable. After the onset of the instability, unstable modes grow approximately in the Alfven time scale and, as a result, a convective motion is excited to change the magnetic field profile until a new state, which is stable against axisymmetric perturbation, is reached. We also find that rotation plays a role in stabilization, although the instability still occurs in the Alfven time scale when the ratio of magnetic energy to rotational kinetic energy is larger than a critical value {approx}0.2. Implication for the evolution of magnetized protoneutron stars is discussed.

• OSTI ID: 21250379
• Journal Information: Physical Review. D, Particles Fields, Vol. 78, Issue 2; Other Information: DOI: 10.1103/PhysRevD.78.024029; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
AXIAL SYMMETRY
CYLINDRICAL CONFIGURATION
DISTURBANCES
EQUATIONS OF STATE
EVOLUTION
GENERAL RELATIVITY THEORY
INSTABILITY
KINETIC ENERGY
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
NEUTRON STARS
PERTURBATION THEORY
ROTATION
SIMULATION
STABILITY
STABILIZATION
TOROIDAL CONFIGURATION