Giant Explosion at the Galactic Center and Huge Shocked Shells in the Halo

We simulate the propagation of a shock front through the galactic halo induced by an explosion and/or a starburst at the galactic center. A huge dumbbell ($\mathrm{\Omega }$)-shaped shock front produced by an explosion of energy $3\times {10}^{56}$ ergs about fifteen million years ago can mimic the radio and X-ray North Polar Spur as well the southern large X-ray spur. The post-shock high-temperature gas in the corona will explain the observed X-ray bulge around the galactic center. Key workds Galaxy: center – Galaxy: halo – Radio continuum: general – Shock wave – X-rays: general