AI 中文总结
研究中子星X射线双星AX J1745.6-2901吸收线速度分量，通过XRISM/Resolve光谱分析，发现其吸收谱有两个极小值，由两个离散速度分量描述，红移分量显著性超3σ，呈现双峰速度分布，为吸收气体运动学提供新观点。
AI 中文摘要
X射线双星中的吸积盘调节着向致密天体的物质转移，并向周围环境驱动辐射和动力学反馈。本文报告了利用XRISM/Resolve对食变中子星低质量X射线双星AX J1745.6-2901进行的X射线光谱分析。相位平均的Fe XXVI Lyα吸收谱显示出两个吸收极小值，其相对深度与单一速度分量预期的理论Lyα1/Lyα2双线比率不一致。我们证明该谱由两个离散速度分量很好地描述：一个蓝移分量v~ -160 km/s和一个红移分量v ~ +590 km/s。基于蒙特卡罗计算，红移分量的显著性超过3σ。这种速度结构在轨道相位上持续存在，不利于局部起源，如凸起或凹陷。蓝移分量远低于外盘逃逸速度，与缓慢外流或盘大气一致。红移吸收体可以用来自失败风的下落气体或引力红移来解释，目前的数据不能排除任何一种可能性。无论其起源如何，红移分量在运动学上与盘大气和外流是分开的。中间速度处没有吸收进一步表明是真正的双峰速度分布而不是单一连续流的两端，为吸收气体运动学提供了新视角。
英文摘要
Accretion disks in X-ray binaries regulate mass transfer onto compact objects and drive radiative and kinetic feedback to their surroundings. Here we report X-ray spectroscopy of the eclipsing neutron star low-mass X-ray binary AX J1745.6-2901 with XRISM/Resolve. The phase-averaged Fe XXVI Lyα absorption profile exhibits two absorption minima with relative depths that are inconsistent with the theoretical Lyα1/Lyα2 doublet ratio expected from a single velocity component. We demonstrate that this profile is well described by two discrete velocity components: a blueshifted component at v~ -160 km/s and a redshifted component at v ~ +590 km/s. The significance of the redshifted component is more than 3 sigma based on a Monte-Carlo calculation. This velocity structure persists across orbital phases, disfavoring a localized origin such as a bulge or dip. The blueshifted component, well below the outer-disk escape velocity, is consistent with a slow outflow or disk atmosphere. The redshifted absorber can be explained either by infalling gas from a failed wind or by a gravitational redshift, and the present data cannot rule out either possibility. Regardless of its origin, the redshifted component is kinematically separate from the disk atmosphere and outflow. The absence of absorption at intermediate velocities further indicates a genuinely bimodal velocity distribution rather than the two ends of a single continuous flow, offering a new view of the absorbing-gas kinematics.
CommentsAccepted by ApJL
