XRISM 揭示 Abell 2029 星系团核心中由晃动驱动的气体运动
XRISM reveals sloshing-driven gas motions in the core of Abell 2029
AI总结：
该研究借助 XRISM Resolve 光谱仪，发现 Abell 2029 星系团核心存在晃动驱动的气体整体运动，其湍流运动对压力支撑和核心加热的贡献有限。
AI中文摘要：
我们利用 XRISM Resolve 光谱仪，研究了弛冷核星系团 Abell 2029 核心内星系团际介质（ICM）的速度结构。我们分析了 XRISM Resolve 的组合观测数据，并将中心区域划分为多个子区域。为了校正 XRISM 点扩散函数导致的光子混合，我们进行了空间-光谱混合分析。我们探测到星系团核心存在有序的视线整体速度梯度：北部区域相对于最亮星系团星系（BCG）呈蓝移，而南部区域接近零速度或呈轻微红移，最大速度差约为 280 km/s。相比之下，湍流速度弥散更小，测量值和上限均≤150 km/s，这意味着非热压力占比低于约 2.5%。该速度模式与钱德拉 X 射线图像中观测到的螺旋结构相关的气体晃动一致。对所有区域取平均后，推断的湍流加热率低于辐射冷却率，表明仅湍流耗散不足以抵消整个核心的冷却。这些结果显示，Abell 2029 并非运动学上无特征：存在由晃动诱导的整体运动，而观测到的视线速度弥散表明其对压力支撑和核心加热的贡献有限。
英文摘要：
We investigate the velocity structure of the intracluster medium (ICM) in the core of the relaxed cool-core cluster Abell 2029 using XRISM Resolve spectroscopy. We analyze combined XRISM Resolve observations and divide the central region into several subregions. To account for photon mixing caused by the XRISM point spread function, we perform a spatial-spectral mixing analysis. We detect an ordered line-of-sight bulk-velocity gradient across the cluster core: the northern regions are blueshifted relative to the brightest cluster galaxy (BCG), while the southern regions are close to zero velocity or slightly redshifted. The maximum velocity difference is about $280~{\rm km\,s^{-1}}$. In contrast, the turbulent velocity dispersion is smaller, with measured values and upper limits of $\lesssim150~{\rm km\,s^{-1}}$, implying a non-thermal pressure fraction below $\sim2.5\%$. The velocity pattern is consistent with gas sloshing associated with the spiral structure seen in Chandra X-ray images. Averaged over all regions, the inferred turbulent heating rate is below the radiative cooling rate, indicating that turbulent dissipation alone is insufficient to offset cooling in the entire core. These results reveal that A2029 is not kinematically featureless: sloshing-induced bulk motions are present, while the observed line-of-sight velocity dispersion indicates only a limited contribution to pressure support and core heating.
