Magnetar Corona

Abstract

Persistent high-energy emission of magnetars is produced by a plasma corona around the neutron star, with total energy output of ~10^{36}erg/s. The corona forms as a result of occasional starquakes that twist the external magnetic field of the star and induce electric currents in the closed magnetosphere. Once twisted, the magnetosphere cannot untwist immediately because of its self-induction. The self-induction electric field lifts particles from the stellar surface, accelerates them, and initiates avalanches of pair creation in the magnetosphere. The created plasma corona maintains the electric current demanded by curl(B) and regulates the self-induction e.m.f. by screening. This corona persists in dynamic equilibrium: it is continually lost to the stellar surface on the light-crossing time and replenished with new particles. In essence, the twisted magnetosphere acts as an accelerator that converts the toroidal field energy to particle kinetic energy. The voltage along the magnetic field lines is maintained near threshold for ignition of pair production, in the regime of self-organized criticality. The voltage is found to be about 1 GeV which is in agreement with the observed dissipation rate \~10^{36}erg/s. The coronal particles impact the solid crust, knock out protons, and regulate the column density of the hydrostatic atmosphere of the star. The transition layer between the atmosphere and the corona is the likely source of the observed 100-keV emission from magnetars. The corona also emits curvature radiation up to 10^{14}Hz and can supply the observed IR-optical luminosity.

9 pages, 6 figures; talk at "Isolated Neutron Stars: from the Interior to the Surface," London, April 2006

References in corpus (18)

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Cited by in corpus (16)

• Formation Rates and Evolution Histories of Magnetars
• Broad-band study with Suzaku of the magnetar class
• General relativistic neutron stars with twisted magnetosphere
• The 2006-2007 Active Phase of Anomalous X-ray Pulsar 4U 0142+61: Radiative and Timing Changes, Bursts, and Burst Spectral Features
• Constraints on the Emission and Viewing Geometry of the Transient Anomalous X-ray Pulsar XTE J1810-197
• Linear acceleration emission: 1 Motion in a large amplitude electrostatic wave
• X-Ray Flares of Gamma-Ray Bursts: Quakes of Solid Quark Stars?
• A rotation-driven pulsar radio emission mechanism
• Unveiling Soft Gamma-Ray Repeaters with INTEGRAL
• The first multi-wavelength campaign of AXP 4U 0142+61 from radio to hard X-rays
• Torsional shear oscillations in the neutron star crust driven by restoring force of elastic stresses
• Broadband Spectral Investigations of Magnetar Bursts
• Are fast radio bursts the birthmark of magnetars?
• The Evolution of High Temperature Plasma in Magnetar Magnetospheres and its Implications for Giant Flares
• Modeling the structure of magnetic fields in Neutron Stars: from the interior to the magnetosphere
• Energy Dependent Intensity Variation of the Persistent X-ray Emission of Magnetars Observed with Suzaku