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arXiv 1909.07409astro-ph.GAastro-ph.HE
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Cosmic-ray驱动的银河系中心外流和磁化射电细丝的起源

Cosmic-ray driven outflow from the galactic center and the origin of magnetized radio filaments

F. Yusef-Zadeh, M. Wardle

摘要:

对银河系中心内部几百秒的无线电、X射线和红外观测凸显了ISM的两个特征。来自分子离子(如H $^+_3$)的宇宙射线电离率至少比银河系圆盘高出两到三个数量级。另一种是远离银河平面的双极X射线和无线电发射。这些特征与高宇宙射线压力驱使大规模风远离银河平面的情景一致。这样的风与恒星风气泡的相互作用可以解释在银河系中心发现的高能非热射电细丝。这种情况的一些影响是去除气体驱动的外流风,作为一种反馈,以减少恒星的形成率在中央分子区(CMZ),和扭曲的方位角磁场线在CMZ的垂直方向远离平面。风和垂直磁场的综合效应可以解释为什么大多数磁化细丝垂直于银河平面。这幅图像表明,我们的银河系核心最近经历了星暴或黑洞活动,正如最近的无线电和X射线观测所表明的那样。

英文摘要:

Radio, X-ray and infrared observations of the inner few hundred pc of the Galactic center have highlighted two characteristics to the ISM. The cosmic ray ionization rate derived from molecular ions such as H$^+_3$, is at least two to three orders of magnitudes higher than in the Galactic disk. The other is bipolar X-ray and radio emission away from the Galactic plane. These features are consistent with a scenario in which high cosmic ray pressure drives large-scale winds away from the Galactic plane. The interaction of such a wind with stellar wind bubbles may explain the energetic nonthermal radio filaments found throughout the Galactic center. Some of the implications of this scenario is the removal of gas driven by outflowing winds, acting as a feedback to reduce the star formation rate in the central molecular zone (CMZ), and the distortion of azimuthal magnetic field lines in the CMZ to vertical direction away from the plane. The combined effects of the wind and vertical magnetic field can explain why most magnetized filaments run perpendicular to the Galactic plane. This proposed picture suggests our Milky Way nucleus has recently experienced starburst or black hole activity, as recent radio and X-ray observations indicate.

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