SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWOCOMPONENT 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 twocomponent 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 selfsimilarly to relativistic velocity ahead of the magnetically driven component. We find that it evolves according to a selfsimilar 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 »
 Authors:
 Kwasan and Hida Observatories, Kyoto University, Kyoto (Japan)
 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: 10.1088/0004637X/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, Email: jin@kusastro.kyotou.ac.jp. SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWOCOMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS. United States: N. p., 2011.
Web. doi:10.1088/0004637X/733/1/18.
Matsumoto, Jin, Asano, Eiji, Shibata, Kazunari, & Masada, Youhei, Email: jin@kusastro.kyotou.ac.jp. SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWOCOMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS. United States. doi:10.1088/0004637X/733/1/18.
Matsumoto, Jin, Asano, Eiji, Shibata, Kazunari, and Masada, Youhei, Email: jin@kusastro.kyotou.ac.jp. Fri .
"SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWOCOMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS". United States.
doi:10.1088/0004637X/733/1/18.
@article{osti_21576799,
title = {SPECIAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATION OF A TWOCOMPONENT OUTFLOW POWERED BY MAGNETIC EXPLOSION ON COMPACT STARS},
author = {Matsumoto, Jin and Asano, Eiji and Shibata, Kazunari and Masada, Youhei, Email: jin@kusastro.kyotou.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 twocomponent 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 selfsimilarly to relativistic velocity ahead of the magnetically driven component. We find that it evolves according to a selfsimilar 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 twocomponent 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 = {10.1088/0004637X/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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