X-Ray Observation of a Magnetized Hot Gas Outflow in the Galactic Center Region

Abstract

We report the discovery of a 1° scale X-ray plume in the northern Galactic Center (GC) region observed with Suzaku. The plume is located at ( l , b ) ∼ (0.°2, 0.°6), east of the radio lobe reported by previous studies. No significant X-ray excesses are found inside or to the west of the radio lobe. The spectrum of the plume exhibits strong emission lines from highly ionized Mg, Si, and S that are reproduced by a thin thermal plasma model with kT  ∼ 0.7 keV and solar metallicity. There is no signature of non-equilibrium ionization. The unabsorbed surface brightness is 3 × 10 −14 erg cm −2  s −1  arcmin −2 in the 1.5–3.0 keV band. Strong interstellar absorption in the soft X-ray band indicates that the plume is not a foreground source but is at the GC distance, giving a physical size of ∼100 pc, density of 0.1 cm −3 , thermal pressure of 1 × 10 −10 erg cm −3 , mass of 600  M ⊙ , and thermal energy of 7 × 10 50 erg. From the apparent association with a polarized radio emission, we propose that the X-ray plume is a magnetized hot gas outflow from the GC.