A Super Bubble Candidate in the Galactic Center and a Local Enhancement G359.77-0.09

Abstract

A 20' × 16' elliptical ring-like structure has been found near the Galactic center in the narrow energy band corresponding to the Kα line from He-like sulfur. In the ring, two diffuse sources are found, a supernova remnant candidate, G359.79-0.26, and an unidentified source, G359.77-0.09. The X-ray spectrum of G359.77-0.09 is similar to that of G359.79-0.26, which can be explained by an absorbed thin thermal plasma model with temperatures of 0.7 and 1.0keV. The absorption column densities of these two sources are large (N_H = 6.9 × 10²² and 4.5 × 10²² cm^-2) and are consistent with that of the Galactic center distance. The X-ray spectrum extracted from the ring-like structure is also represented by an absorbed thin thermal plasma model (kT_e ∼ 0.9keV). The thermal energy of the plasma filling the ring-like structure is estimated to be 1.0 × 10⁵¹erg. We therefore propose that the two sources comprise a single ring-like object, which is possibly a super bubble with a size of 49pc × 40pc in the Galactic center region.