1-3 November 2006 2nd EAST-ASIA NUMERICAL ASTROPHYSICS MEETING(KASI, Daejeon, Korea)

Numerical Simulations of RelativisNumerical Simulations of Relativistic Expansion of tic Expansion of

Magnetic Arcades in MagnetarsMagnetic Arcades in Magnetars

Eiji Asano1, Hiroyuki Takahashi1

andRyoji Matsumoto2

1:Graduate School of Science and Technology, Chiba University2:Department of Physics, Faculty of Science, Chiba University

Soft Soft -ray Repeaters-ray Repeaters

According to a model of soft -ray repeaters proposed by Thompson & Duncan (2001), we simulated the relativistic expansion of magnetic arcades.

To study the mechanism of the releasing energy in magnetars, we carried out simulations of two models relativistic force-free equations.

The codes are based on HLL method.

(NASA Marshall Spaceflight Center)

SimulationsSimulations

Local simulation (2.5D Relativistic MHD eqs.)

Model A: Interaction of neutron star and its disk (Asano et al., 2005) This model can be applied the disk is formed around the magnetar.

Result: Magnetic loops connecting neutron star and its disk is twisted, they expand relativistic speed.

Result: The plasma velocity reaches the speed of light in the case of a strongly magnetic field.

SimulationsSimulations

Model B: Isolated neutron star A tangled magnetic field inside a magnetar creates rising magnetic arcades.

Result: When critical twist is accumulated in the arcades, the relativistic expansion of magnetic arcades occur.

(Lorents factor >10)