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Title: SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWO-COMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS

Abstract

The nonlinear dynamics of outflows driven by magnetic explosion on the surface of a compact star is investigated through special relativistic magnetohydrodynamic simulations. We adopt, as the initial equilibrium state, a spherical stellar object embedded in hydrostatic plasma which has a density {rho}(r) {proportional_to} r{sup -}{alpha} and is threaded by a dipole magnetic field. The injection of magnetic energy at the surface of a compact star breaks the equilibrium and triggers a two-component outflow. At the early evolutionary stage, the magnetic pressure increases rapidly around the stellar surface, initiating a magnetically driven outflow. A strong forward shock driven outflow is then excited. The expansion velocity of the magnetically driven outflow is characterized by the Alfven velocity on the stellar surface and follows a simple scaling relation v{sub mag} {proportional_to} v{sub A}{sup 1/2}. When the initial density profile declines steeply with radius, the strong shock is accelerated self-similarly to relativistic velocity ahead of the magnetically driven component. We find that it evolves according to a self-similar relation {Gamma}{sub sh} {proportional_to} r{sub sh}, where {Gamma}{sub sh} is the Lorentz factor of the plasma measured at the shock surface r{sub sh}. A purely hydrodynamic process would be responsible for the acceleration mechanism ofmore » the shock driven outflow. Our two-component outflow model, which is the natural outcome of the magnetic explosion, can provide a better understanding of the magnetic active phenomena on various magnetized compact stars.« less

Authors:
; ;  [1];  [2]
  1. Kwasan and Hida Observatories, Kyoto University, Kyoto (Japan)
  2. Graduate School of System Informatics, Department of Computational Science, Kobe University, Kobe (Japan)
Publication Date:
OSTI Identifier:
21576799
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 733; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/733/1/18
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; EXPLOSIONS; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; SIMULATION; STARS; VELOCITY; FLUID MECHANICS; HYDRODYNAMICS; MECHANICS

Citation Formats

Matsumoto, Jin, Asano, Eiji, Shibata, Kazunari, and Masada, Youhei, E-mail: jin@kusastro.kyoto-u.ac.jp. SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWO-COMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS. United States: N. p., 2011. Web. doi:10.1088/0004-637X/733/1/18.
Matsumoto, Jin, Asano, Eiji, Shibata, Kazunari, & Masada, Youhei, E-mail: jin@kusastro.kyoto-u.ac.jp. SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWO-COMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS. United States. doi:10.1088/0004-637X/733/1/18.
Matsumoto, Jin, Asano, Eiji, Shibata, Kazunari, and Masada, Youhei, E-mail: jin@kusastro.kyoto-u.ac.jp. Fri . "SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWO-COMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS". United States. doi:10.1088/0004-637X/733/1/18.
@article{osti_21576799,
title = {SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWO-COMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS},
author = {Matsumoto, Jin and Asano, Eiji and Shibata, Kazunari and Masada, Youhei, E-mail: jin@kusastro.kyoto-u.ac.jp},
abstractNote = {The nonlinear dynamics of outflows driven by magnetic explosion on the surface of a compact star is investigated through special relativistic magnetohydrodynamic simulations. We adopt, as the initial equilibrium state, a spherical stellar object embedded in hydrostatic plasma which has a density {rho}(r) {proportional_to} r{sup -}{alpha} and is threaded by a dipole magnetic field. The injection of magnetic energy at the surface of a compact star breaks the equilibrium and triggers a two-component outflow. At the early evolutionary stage, the magnetic pressure increases rapidly around the stellar surface, initiating a magnetically driven outflow. A strong forward shock driven outflow is then excited. The expansion velocity of the magnetically driven outflow is characterized by the Alfven velocity on the stellar surface and follows a simple scaling relation v{sub mag} {proportional_to} v{sub A}{sup 1/2}. When the initial density profile declines steeply with radius, the strong shock is accelerated self-similarly to relativistic velocity ahead of the magnetically driven component. We find that it evolves according to a self-similar relation {Gamma}{sub sh} {proportional_to} r{sub sh}, where {Gamma}{sub sh} is the Lorentz factor of the plasma measured at the shock surface r{sub sh}. A purely hydrodynamic process would be responsible for the acceleration mechanism of the shock driven outflow. Our two-component outflow model, which is the natural outcome of the magnetic explosion, can provide a better understanding of the magnetic active phenomena on various magnetized compact stars.},
doi = {10.1088/0004-637X/733/1/18},
journal = {Astrophysical Journal},
number = 1,
volume = 733,
place = {United States},
year = {Fri May 20 00:00:00 EDT 2011},
month = {Fri May 20 00:00:00 EDT 2011}
}
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