Two-Dimensional Numerical MHD Simulation of Magnetic Reconnection in Galaxy

Abstract

X-ray astronomy satellites detected strong X-ray emission along Galactic ridge, called Galactic Ridge X-ray Emission (GRXE), which is thermal emission of super-hot diffuse plasma. It has been revealed that GRXE plasma is composed of mainly hot (7 keV) component and cool (0.8 keV) component (Kaneda et al. 1997). Origin and nature of the hot component is not known while the cool component is made of supernova remnants. We recently showed that a supernova (or other point explosion) and the Parker instability trigger magnetic reconnection, and we proposed a possible mechanism to explain the origin of GRXE (Tanuma et al. 1998; Yokoyama & Shibata 1995). We solved 2D resistive MHD equations numerically to examine the magnetic reconnection triggered by a supernova and Parker instability. We find that the reconnection heats the interstellar gas from 0.7 keV to 8 keV if local interstellar magnetic field strength is 30 μG. The re-connection accelerates and heats the interstellar medium. Magnetic islands are generated and confine the heated plasma. Thus, we propose that the reconnection is triggered by a point explosion, Parker instability, the collision of interstellar clouds etc., and reconnection can explain X-rays from Galactic ridge and halo.