银河系外首个球状星团恒星流的证据
Evidence for the First Globular Cluster Stellar Stream beyond the Milky Way
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中文总结 AI 辅助
本研究在超弥散星系UGC9050-Dw1中发现首个银河系外球状星团恒星流，通过生成式流建模约束其前身质量，为超弥散星系暗物质晕提供了首个基于恒星流的观测约束，拓展了暗物质科学的研究范畴。
中文摘要 AI 辅助
超弥散星系的暗物质含量是一个备受争议的课题。恒星流由宿主星系潮汐剥离其轨道运行的恒星系统中的恒星形成，是约束外部星系暗物质含量的有力技术，被剥离的恒星会形成持续数十亿年的细长前导尾和后随尾潮汐臂。来自球状星团的恒星流是暗物质晕和子结构的特别敏感探针，球状星团流本应存在于多种类型的宿主星系中，但迄今为止仅在银河系中观测到。我们通过哈勃空间望远镜对超弥散星系UGC9050-Dw1的深场成像，提供了首个银河系外球状星团恒星流的证据。该流的形态、颜色及其与一个致密源的视关联，在观测上支持其源自球状星团前身的解释，且我们通过模拟球状星团恒星族重现了观测到的表面亮度。我们采用生成式恒星流建模方法，将动力学模型直接拟合至恒星流形态，以约束前身天体的质量，并给出了首个基于恒星流的超弥散星系暗物质晕约束结果。恒星流模型指向球状星团起源，并暗示宿主星系存在大质量暗物质晕。通过将球状星团流分析的范围扩展至外部星系，本研究为暗物质科学开启了新的篇章。
英文摘要
The dark matter content of ultra-diffuse galaxies is the subject of considerable debate. Stellar streams, which form when a host galaxy tidally strips stars from an orbiting stellar system, provide a powerful technique to constrain the dark matter content of external galaxies. The stripped stars form long, thin leading and trailing tidal arms that persist for billions of years. Stellar streams from globular clusters are particularly sensitive probes of dark matter halos and substructure. Globular cluster streams are expected to exist in a variety of host galaxy types, but so far, they have only been observed in the Milky Way. We present evidence for the first extragalactic globular cluster stellar stream, identified in deep Hubble Space Telescope imaging of the ultra-diffuse galaxy, UGC9050-Dw1. The stream's morphology, colour, and apparent association with a compact source support the globular cluster progenitor interpretation observationally, and we reproduce the observed surface brightness with simulated globular cluster stellar populations. We use generative stream modelling, which fits dynamical models directly to the stream morphology, to constrain the mass of the progenitor and present the first stream-based halo constraint for an ultra-diffuse galaxy. The stream models point to a globular cluster origin and suggest a massive dark matter host halo. By extending the reach of globular cluster stream analysis to external galaxies, this work opens a new chapter in dark matter science.
