For most of their lifetime, super-massive black holes (SMBHs) commonly found in galactic nuclei obtain mass from the ambient medium at a rate well below the Eddington limit¹, which is mediated by a radiatively inefficient, hot accretion flow². Both theory and numerical simulations predict that a strong wind must exist in such hot accretion flows^3,4,5,6. The wind is of special interest not only because it is an indispensable ingredient of accretion but also, perhaps more importantly, because it is believed to play a crucial role in the evolution of the host galaxy via the so-called kinetic mode active galactic nucleus feedback^7,8. Observational evidence for this wind, however, remains scarce and indirect^9,10,11,12. Here we report the detection of a hot outflow from the low-luminosity active galactic nucleus in M81, based on Chandra high-resolution X-ray spectroscopy. The outflow is evidenced by a pair of Fe xxvi Lyα lines redshifted and blueshifted at a bulk line-of-sight velocity of ±2.8 × 10³ km s⁻¹ and a high line ratio of Fe xxvi Lyα to Fe xxv Kα implying a plasma temperature of 1.3 × 10⁸ K. This high-velocity, hot plasma cannot be produced by stellar activity or the accretion inflow onto the SMBH. Our magnetohydrodynamical simulations show that, instead, it is naturally explained by a wind from the hot accretion flow, propagating out to ≳10⁶ times the gravitational radius of the SMBH. The kinetic energy and momentum of this wind can significantly affect the evolution of the circumnuclear environment and beyond.

在其生命周期的大部分时间里，通常在星系核中发现的超大质量黑洞 (SMBH) 从周围介质中获取质量的速度远低于爱丁顿极限¹，这是由辐射效率低下的热吸积流²介导的。理论和数值模拟都预测，在这种热吸积流中一定存在强风^3,4,5,6。风之所以特别有趣，不仅因为它是吸积不可或缺的成分，而且或许更重要的是，它被认为通过所谓的动力学模式主动星系核反馈在宿主星系的演化中发挥着至关重要的作用^7,8。然而，这种风的观测证据仍然稀缺和间接^9,10,11,12. 在这里，我们报告了基于钱德拉高分辨率 X 射线光谱仪检测到 M81 中低光度活动星系核的热流出。流出由一对以 ±2.8 × 10 ³  km s ^-1的整体视线速度红移和蓝移的 Fe xxv​​i Lyα 线和 Fe xxv​​i Lyα 与 Fe  xxv Kα的高线比 暗示等离子体的证明温度为 1.3 × 10 ⁸  K。这种高速、热等离子体不能由恒星活动或吸积流入 SMBH 产生。我们的磁流体动力学模拟表明，相反，它可以自然地用来自热吸积流的风来解释，传播到≳ 10 ⁶乘以 SMBH 的引力半径。这种风的动能和动量可以显着影响环核环境及其他环境的演变。