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

• Published in: The Astrophysical journal 2019-04, Vol.875 (1), p.32
• Main Authors: Nakashima, Shinya, Koyama, Katsuji, Wang, Q. Daniel, Enokiya, Rei
• Format: Article
• Language: English
• Subjects: Astrophysics; Emission lines; Galaxy: center; Interstellar; Ionization; ISM: jets and outflows; magnetic fields; Metallicity; Nonequilibrium ionization; Outflow; Radio emission; Soft x rays; Surface brightness; Thermal energy; Thermal plasmas; X-rays: galaxies
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ab0d82

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 × 1050 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.