Special relativistic magnetohydrodynamic simulation of a two-component outflow powered by magnetic explosion on compact stars

Jin Matsumoto, Youhei Masada, Eiji Asano, Kazunari Shibata

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

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 ρ(r) r ∝ 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 Alfvén velocity on the stellar surface and follows a simple scaling relation vmag ∝ vA1/2. 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 Γsh r ∝ sh, where Γsh is the Lorentz factor of the plasma measured at the shock surface r 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.

Original languageEnglish
Article number18
JournalAstrophysical Journal
Volume733
Issue number1
DOIs
Publication statusPublished - 2011 May 20
Externally publishedYes

Keywords

  • magnetohydrodynamics (MHD)
  • methods: numerical
  • relativistic processes
  • stars: neutron
  • stars: winds, outflows

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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