标题： XRISM 对蛇夫座星系团的观测：动态扰动核心中的静止速度结构 显示英文标题

标题： XRISM Observation of the Ophiuchus Galaxy Cluster: Quiescent Velocity Structure in the Dynamically Disturbed Core

摘要： 我们介绍了使用XRISM卫星对蛇夫座星系团核心的高分辨率X射线光谱观测。尽管以前的观测揭示了星系团核心中存在多个冷前缘和动力学扰动，但我们的XRISM观测显示，在内部区域（~< 25 kpc）气体速度弥散度为\sigma _v = 115 +/- 7 km s^{-1}，在外部区域（~ 25-50 kpc）为\sigma _v = 186 +/- 9 km s^{-1}。气体温度分别为内区kT = 5.5 +/- 0.2 keV和外区kT = 8.4 +/- 0.2 keV，金属丰度分别为Z = 0.75 +/- 0.03 Z_sun（内区）和0.44 +/- 0.02 Z_sun（外区）。测得的速度弥散度对应于非热压力分数仅为1.4 +/- 0.2%（内区）和2.5 +/- 0.2%（外区），表明湍流高度亚音速。我们对整体气体运动的分析表明，内区气体相对于中心星系几乎静止（|v_bulk|=8 +/- 7 km s^{-1}），而外区则表现出中等运动（|v_bulk|=104 +/- 7 km s^{-1}）。假设速度弥散度来源于湍流运动，湍流加热率仅为辐射冷却率的约40%，尽管存在一定不确定性。这表明气体的加热和冷却并不平衡。中心活动星系核（AGN）的活动显然减弱了。造成冷前缘的摆动运动现在可能接近速度最小的转折点。 显示英文摘要

摘要： We present the high-resolution X-ray spectroscopic observations of the Ophiuchus galaxy cluster core using the XRISM satellite. Despite previous observations revealing multiple cold fronts and dynamical disturbances in the cluster core, our XRISM observations show low gas velocity dispersions of \sigma_v = 115 +/- 7 km s^{-1} in the inner region (~< 25 kpc) and \sigma_v = 186 +/- 9 km s^{-1} in the outer region (~ 25-50 kpc). The gas temperatures are kT = 5.5 +/- 0.2 keV and 8.4 +/- 0.2 keV for the inner and outer regions, respectively, with metal abundances of Z = 0.75 +/- 0.03 Z_sun (inner) and 0.44 +/- 0.02 Z_sun (outer). The measured velocity dispersions correspond to nonthermal pressure fractions of only 1.4 +/- 0.2% (inner) and 2.5 +/- 0.2% (outer), indicating highly subsonic turbulence. Our analysis of the bulk gas motion indicates that the gas in the inner region is nearly at rest relative to the central galaxy (|v_bulk|=8 +/- 7 km s^{-1}), while the outer region exhibits a moderate motion of |v_bulk|=104 +/- 7 km s^{-1}. Assuming the velocity dispersion arises from turbulent motions, the turbulent heating rate is only ~ 40% of the radiative cooling rate, although there is some uncertainty. This suggests that the heating and cooling of the gas are not balanced. The activity of the central active galactic nucleus (AGN) has apparently weakened. The sloshing motion that created the cold fronts may now be approaching a turning point at which the velocity is minimum.