发表机构
University of Nottingham; École Polytechnique Fédérale de Lausanne (EPFL); Universidad de La Laguna; Instituto de Astrofísica de Canarias; Universidad Autónoma de Madrid（诺丁汉大学; 洛桑联邦理工学院; 拉帕尔马大学; 加那利天体物理研究所; 马德里自治大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过动力学摩擦和潮汐剥离，提出基于物理的星系团中央星系与弥散光定义，并用模拟验证其与观测选择高度一致。
AI 中文摘要
在星系团中，通常会在概念上区分中央最亮星系（BCG）与更弥散的星系团内光（ICL）。然而，迄今为止，这种区分缺乏清晰的物理基础，使理论和观测研究都感到困惑。我们通过提出一种基于动力学动机的两种恒星成分定义来解决这一问题，并使用“三百”项目中的星系团放大模拟进行评估。我们首先采用一种动机性的后报方法，稳健地追踪107个现今星系团中心恒星穿过并合层级的历史。我们发现，最终BCG恒星质量的大部分通常仅由3至5个前身暗晕的中心星系贡献。大多数被吸积的星系不向BCG贡献恒星，而是作为卫星存活或在星系团各处沉积恒星物质。这自然导致将BCG恒星族群定义为源自质量最大的内落系统的中心星系。这些恒星通过有效的动力学摩擦被输送到星系团中心，随后经历剧烈弛豫。ICL则来自互补的恒星族群，即从所有内落系统外围被潮汐剥离的恒星。因此，我们开发了一种预报方法，通过其起源恒星系统的动力学命运来识别BCG和ICL中的恒星。将此方法应用于261个星系团，我们发现所得成分在空间上仍然相互交织，但在相空间中占据不同区域。我们物理定义的BCG与基于孔径的传统选择具有高完备性，同时提供了层级组装的直接解释。
英文摘要
In galaxy clusters, it is common to conceptually distinguish the central, brightest cluster galaxy (BCG) from the more diffuse intracluster light (ICL). So far, however, this distinction has lacked a clear physical basis, confusing both theoretical and observational studies. We address this by presenting a dynamically motivated definition of the two stellar components, evaluated using cluster zoom simulations from the Three Hundred project. We start with a motivational hindcasting approach, robustly tracing stars from the centres of 107 present-day clusters back through the merger hierarchy. We find that the majority of the final BCG stellar mass is typically contributed by the central galaxies of only 3 to 5 progenitor haloes. Most accreted galaxies contribute no stars to the BCG, instead surviving as satellites or depositing stellar material throughout the cluster. This naturally leads to a definition of the BCG stellar population as originating from the central galaxies of the most massive infalling systems. These are delivered to the cluster centre via efficient dynamical friction and subsequently undergo violent relaxation. The ICL arises from the complementary population of stars tidally stripped from the outskirts of all infalling systems. We therefore develop a forecasting method, identifying stars in the BCG and ICL via the dynamical fates of their originating stellar systems. Applying this to 261 clusters, we find the resulting components remain spatially interleaved, but occupy distinct regions of phase space. Our physically defined BCG matches conventional aperture-based selections with high completeness, while providing a direct interpretation in terms of hierarchical assembly.
CommentsAccepted for publication, MNRAS. 18 pages, 16 figures
