Ram pressure stripping of disk galaxies
Ram pressure stripping of disk galaxies
复制标题
盘状星系的冲压压力剥离
DOI：
--
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
U. Vienna
中科院分区：
文献类型：
--
作者：
E. Roediger;G. Hensler;Institute for Theoretical Physics;Astrophysics Kiel;U. Vienna
星系存在于各种环境中，从孤立的场星系、星系群到星系团。除了星系之外，星系团和星系团中还充满了热的稀薄气体，即星系团内介质（intracluster medium）或星系团内介质（intracluster medium）。对不同环境中的星系，特别是盘星系进行比较观测，揭示了它们在形态、颜色、星星形成活动和气体含量方面的系统差异。理论工作已经提出了几种机制，可以在集群和集团的工作。一方面，星系之间存在（引力）相互作用，另一方面，星系与ICM之间存在相互作用。后者的基本思想是，星系在穿过ICM时会被冲压压力剥离其气体。这些气体是形成星星的原材料，因此这种冲压压力剥离（RPS）对星系有着严重的影响。本文的目的是用流体动力学模拟方法研究盘星系的RPS过程。这项工作中的模拟仅限于正面的情况，这允许我们使用2D代码。这使我们能够使用高分辨率和编译一个全面的参数研究，不同的星系属性以及ICM条件。我们发现，RPS进行三个阶段：第一个瞬时剥离阶段，第二个动态的中间阶段，第三个准稳定的连续粘性剥离阶段。汽提效率与ICM流的马赫数略有关系，但主要参数是冲压压力。对于固定的星系气体面密度，汽提效率不依赖于气体盘的垂直结构和厚度。汽提效率的数值计算结果与分析估计吻合得很好。从我们的模拟中，我们得出结论，在高密度环境（如集群中心）的星系气体盘严重截断，甚至完全剥离。但是，低密度环境（星系团外围或星系团）中的气体盘也会受到ICM流和回落物质的干扰，因此它们也应该进行预处理。
Galaxies exist in various environments, ranging from isolated field galaxies over galaxy groups to clusters. In addition to galaxies, clusters and groups are filled with a hot tenuous gas, the intracluster medium or intragroup medium (abbreviated ICM for both). Comparative observations of galaxies, especially disk galaxies, in various environments reveal systematic differences in morphology, colour, star formation activity and gas contents. Theoretical work has proposed several mechanisms that can be at work in clusters and groups. On the one hand there are (gravitational) interactions among the galaxies themselves, on the other hand there is the interaction between the galaxies and the ICM. The basic idea for the latter is that a galaxy is stripped of its gas by ram pressure as it moves through the ICM. The gas is the raw material for star formation, therefore such ram pressure stripping (RPS) has severe consequences for a galaxy. The aim of this work is to study the process of RPS of disk galaxies with hydrodynamical simulations. The simulations in this work are restricted to the face-on case, which allows us to use a 2D code. This enables us to use high resolution and to compile a comprehensive parameter study that varies galaxy properties as well as ICM conditions. We find that RPS proceeds in three phases: firstly the instantaneous stripping phase, secondly the dynamic intermediate phase, and thirdly the quasi-stable continuous viscous stripping phase. The stripping efficiency depends slightly on the Mach number of the ICM flow, however, the main parameter is the ram pressure. For a fixed galactic gas surface density the stripping efficiency does not depend on the vertical structure and thickness of the gas disk. The numerical results for the stripping efficiency are in good agreement with analytical estimates. From our simulations we conclude that gas disks of galaxies in high density environments (like cluster centres) are heavily truncated or even completely stripped. But also the gas disks of galaxies in low density environments (cluster outskirts or groups) are disturbed by the ICM-flow and back-falling material, so that they should also be pre-processed.