Three-Dimensional Numerical Magnetohydrodynamic Simulations of Magnetic Reconnection in the Interstellar Medium

Abstract

Strong thermal X-ray emission, called Galactic Ridge X-ray Emission, is observed along the Galactic plane (Koyama et al. 1986). The origin of hot (7 keV) component of GRXE is not known, while cool (0.8 keV) one is associated with supernovae (Kaneda et al. 1997, Sugizaki et al. 2001). We propose a possible mechanism to explain the origin; locally strong magnetic fields of heat interstellar gas to 7 keV via magnetic reconnection (Tanuma et al. 1999). There will be the small-scale ( by integration of Faraday Rotation Measure, if it is localized by a volume filling factor of f 0.1. In order to examine this model, we solved three-dimensional (3D) resistive magnetohydrodynamic (MHD) equations numerically to examine the magnetic reconnect ion triggered by a supernova shock (fig.l). We assume that the magnetic field is Bx = 30tanh(y/20pc) G, By = Bz = 0, and the temperature is uniform, at the initial condition. We put a supernova explosion outside the current sheet. The supernova-shock, as a result, triggers the magnetic reconnect ion, and the gas is heatd to > 7 keV. The magnetic reconnect ion heats the interstellar gas to 7 keV in the Galactic plane, if it occurs in the locally strong magnetic fields of . The heated plasma is confined by the magnetic field for . The required interval of the magnetic reconnect ions (triggered by anything) is 1 - 10 yr. The magnetic reconnect ion will explain the origin of X-rays from the Galactic ridge, furthermore the Galactic halo, and clusters of galaxies.