通过引力弧成像揭示z~1时群内介质中的大尺度旋转运动
Unveiling large-scale rotational motions in the intragroup medium at z~1 through gravitational-arc tomography
AI总结：
研究通过引力弧成像分析z=1.167的星团中冷群内介质的分布和动力学，发现其具有旋转特征和潮汐剥离影响，估计总气体质量为1.3-2.5×10^11 Msol。
摘要：
我们首次对z=1.167确认的星团中的冷群内介质（IGrM）进行了空间分辨的表征。利用30条独立视线方向指向引力透镜星系SGAS J0033+02的背景光，结合场中各种源，绘制了该星团中弥散、金属富集气体的分布和动力学。检测到延伸至62 kpc的MgII、FeII、CaII和MgI吸收线，与一个大质量恒星形成螺旋星系及其相互作用伴星相连。这些与另外四个成员一起形成一个半径为313 kpc的紧凑星团。向下延伸的蓝移吸收指示出流。该气体的分布和二维动力学表明潮汐剥离和恒星形成驱动的风的影响。场中干涉吸收部分追踪内部星系运动。简单叠加单个盘无法再现大影响参数或反向旋转区域的速度场，而一个全局IGrM晕具有~130 km/s的旋转速度可良好匹配。除了个别星系外壳外，数据与一个与星系协同旋转的群尺度结构一致。假设动态平衡，我们估计总（冷+暖+热）气体质量为1.3-2.5×10^11 Msol，存在较大的系统性不确定性，对应约50%的所有物质，在群的四分之一virial半径内。这些结果表明，冷（~10^4 K）云嵌套在动态一致的群尺度晕中。气体似乎与群引力束缚，而非重新吸积到个别星系中。
英文摘要：
We present the first spatially resolved characterisation of the cool intragroup medium (IGrM) in a spectroscopically confirmed galaxy group at z=1.167. Using 30 independent sightlines towards the gravitationally lensed galaxy SGAS J0033+02, we combine background light from an extended gravitational arc and various sources in the field to map the distribution and kinematics of diffuse, metal-enriched gas pertaining to the group. We detect prominent MgII, FeII, CaII, and MgI absorption extending up to 62 kpc from a massive star-forming spiral galaxy and its interacting companion. Together with four other members, these form a compact group with a virial radius of 313 kpc. Down-the-barrel, blueshifted absorption indicates outflows. The distribution and two-dimensional kinematics of this gas suggest the influence of tidal stripping and star formation-driven winds. Intervening absorption across the field partly traces internal galaxy motions. A simple superposition of individual discs cannot reproduce the velocity field at large impact parameters or in counter-rotating regions, while a global IGrM halo with a rotational velocity of ~130 km/s provides a good match. Beyond individual galaxy envelopes, the data are consistent with a group-scale structure that co-rotates in concert with the galaxies. Assuming dynamical equilibrium, we estimate a total (cool+warm+hot) gas mass of 1.3-2.5x10^11 Msol, with large systematic uncertainties, corresponding to approximately 50% of all baryons, within one-quarter of the group's virial radius. These results point to a multiphase IGrM in which cool (~10^4 K) clouds are embedded within a dynamically coherent, group-wide halo. The gas appears gravitationally bound to the group rather than reaccreting onto individual galaxies.
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