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

We report the discovery of a $1^{\circ }$ scale X-ray plume in the northern Galactic Center (GC) region observed with Suzaku. The plume is located at ($l$, $b$) $\sim$ (0\mbox{.!!^\circ}2, 0\mbox{.!!^\circ}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 is reproduced by a thin thermal plasma model with $kT\sim 0.7$ keV and solar metallicity. There is no signature of non-equilibrium ionization. The unabsorbed surface brightness is $3\times {10}^{-14}$ 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 $\sim$100 pc, a density of 0.1 cm${}^{-3}$, thermal pressure of $1\times {10}^{-10}$ erg cm${}^{-3}$, mass of 600 $M_{\odot }$ and thermal energy of $7\times {10}^{50}$ 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.