Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany.
Space Research Institute of the Russian Academy of Sciences, Moscow, Russia.
Nature. 2020 Dec;588(7837):227-231. doi: 10.1038/s41586-020-2979-0. Epub 2020 Dec 9.
The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection into the halo from past activity in the nucleus of the Milky Way; however, the origin of this energy (star formation or supermassive-black-hole activity) is uncertain, and the causal connection between nuclear structures and large-scale features has not been established unequivocally. Here we report soft-X-ray-emitting bubbles that extend approximately 14 kiloparsecs above and below the Galactic centre and include a structure in the southern sky analogous to the North Polar Spur. The sharp boundaries of these bubbles trace collisionless and non-radiative shocks, and corroborate the idea that the bubbles are not a remnant of a local supernova but part of a vast Galaxy-scale structure closely related to features seen in γ-rays. Large energy injections from the Galactic centre are the most likely cause of both the γ-ray and X-ray bubbles. The latter have an estimated energy of around 10 erg, which is sufficient to perturb the structure, energy content and chemical enrichment of the circumgalactic medium of the Milky Way.
银河系的光环为研究星系形成模型所预测的被冲击波加热的热气体的性质提供了一个实验室。有观测证据表明，银河系核心过去的活动向光环注入了能量；然而，这种能量的来源（恒星形成或超大质量黑洞活动）尚不确定，核结构与大规模结构之间的因果关系也没有得到明确确立。在这里，我们报告了软 X 射线发射的气泡，这些气泡在银河系中心上方和下方延伸约 14 千秒差距，其中包括类似于北磁极刺的南部天空结构。这些气泡的锐利边界追踪了无碰撞和非辐射性冲击波，并证实了这样一个观点，即这些气泡不是局部超新星的残余物，而是与在γ射线中看到的特征密切相关的巨大星系尺度结构的一部分。来自银河系中心的大量能量注入是γ射线和 X 射线气泡最有可能的原因。后者的能量估计约为 10 尔格，足以干扰银河系的星系际介质的结构、能量含量和化学丰度。
