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

Abstract

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 $3\\times10^{-14}$ 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 $1\\times10^{-10}$ erg cm$^{-3}$, mass of 600 $M_\\odot$ and thermal energy of $7\\times10^{50}$ 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.