Triggering an aurora

Ambient ionospheric electron density studied as triggering mechanism of aurora

Van Allen belt plasma physics

Plasma turbulence in Van Allen bel

A limit on stably trapped particle fluxes

Limits of stably trapped particle fluxes - behavior of Whistler and ion cyclotron noise mode

Investigation of magnetospheric physics Technical status report, period ending 31 Mar. 1967

Magnetospheric physics - auroral zone structur

Fan-shaped jets in three dimensional reconnection simulation as a model of ubiquitous solar jets

Magnetic reconnection is a fundamental process in space and astrophysical plasmas in which oppositely directed magnetic fields changes its connectivity and eventually converts its energy into kinetic and thermal energy of the plasma. Recently, ubiquitous jets (for example, chromospheric anemone jets, penumbral microjets, umbral light bridge jets) have been observed by Solar Optical Telescope on board the satellite Hinode. These tiny and frequently occurring jets are considered to be a possible evidence of small-scale ubiquitous reconnection in the solar atmosphere. However, the details of three dimensional magnetic configuration are still not very clear. Here we propose a new model based on three dimensional simulations of magnetic reconnection using a typical current sheet magnetic configuration with a strong guide field. The most interesting feature is that the jets produced by the reconnection eventually move along the guide field lines. This model provides a fresh understanding of newly discovered ubiquitous jets and moreover a new observational basis for the theory of astrophysical magnetic reconnection.Comment: 11 pages, 4 figures, Accepted for publication in The Astrophysical Journal Letter

Experiments with Magnetohydrodynamically Supported Shock Layers

Shock tube experiments to determine interaction of hypersonic flow with magnetic fiel

Gamma-burst emission from neutron-star accretion

A model for emission of the hard photons of gamma bursts is presented. The model assumes accretion at nearly the Eddington limited rate onto a neutron star without a magnetic field. Initially soft photons are heated as they are compressed between the accreting matter and the star. A large electric field due to relatively small charge separation is required to drag electrons into the star with the nuclei against the flux of photons leaking out through the accreting matter. The photon number is not increased substantially by Bremsstrahlung or any other process. It is suggested that instability in an accretion disc might provide the infalling matter required

Resistive Magnetohydrodynamic Simulations of Relativistic Magnetic Reconnection

Resistive relativistic magnetohydrodynamic (RRMHD) simulations are applied to investigate the system evolution of relativistic magnetic reconnection. A time-split Harten--Lan--van Leer method is employed. Under a localized resistivity, the system exhibits a fast reconnection jet with an Alfv\'{e}nic Lorentz factor inside a narrow Petschek-type exhaust. Various shock structures are resolved in and around the plasmoid such as the post-plasmoid vertical shocks and the "diamond-chain" structure due to multiple shock reflections. Under a uniform resistivity, Sweet--Parker-type reconnection slowly evolves. Under a current-dependent resistivity, plasmoids are repeatedly formed in an elongated current sheet. It is concluded that the resistivity model is of critical importance for RRMHD modeling of relativistic magnetic reconnection.Comment: published in ApJ