Environment plays a critical role in shaping the assembly of low-mass galaxies. Here, we use the UniverseMachine (UM) galaxy–halo connection framework and Data Release 3 of the Satellites Around Galactic Analogs (SAGA) Survey to place dwarf galaxy star formation and quenching into a cosmological context. UM is a data-driven forward model that flexibly parameterizes galaxy star formation rates (SFRs) using only halo mass and assembly history. We add a new quenching model to UM, tailored for galaxies with m _⋆ ≲ 10⁹ M _⊙, and constrain the model down to m _⋆ ≳ 10⁷ M _⊙ using new SAGA observations of 101 satellite systems around Milky Way (MW)–mass hosts and a sample of isolated field galaxies in a similar mass range from the Sloan Digital Sky Survey. The new best-fit model, “UM-SAGA,” reproduces the satellite stellar mass functions, average SFRs, and quenched fractions in SAGA satellites while keeping isolated dwarfs mostly star-forming. The enhanced quenching in satellites relative to isolated field galaxies leads the model to maximally rely on halo assembly to explain the observed environmental quenching. Extrapolating the model down to m _⋆ ∼ 10^6.5 M _⊙ yields a quenched fraction of ≳30% for isolated field galaxies and ≳80% for satellites of MW-mass hosts at this stellar mass. Spectroscopic surveys can soon test this specific prediction to reveal the relative importance of internal feedback, cessation of mass and gas accretion, satellite-specific gas processes, and reionization for the evolution of faint low-mass galaxies.

中文翻译：

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SAGA 调查。V. 使用更新的 UniverseMachine 对银河系质量星系周围的卫星系统进行建模


环境在塑造低质量星系的组装中起着至关重要的作用。在这里，我们使用 UniverseMachine （UM） 星系-光晕连接框架和银河系模拟卫星 （SAGA） 巡天的数据版本 3，将矮星系恒星的形成和淬灭置于宇宙学背景下。UM 是一种数据驱动的正向模型，它仅使用光晕质量和组装历史灵活地参数化星系恒星形成速率 （SFR）。我们在 UM 中添加了一个新的猝灭模型，为 m_⋆ ≲ 10⁹M_⊙ 的星系量身定制，并使用对银河系 （MW） 周围 101 个卫星系统的新 SAGA 观测——质量主机和来自斯隆数字巡天（Sloan Digital Sky Survey）的类似质量范围内的孤立场星系样本，将模型限制为 m_⋆ ≳^{10 7}M_⊙新的最佳拟合模型“UM-SAGA”再现了 SAGA 卫星中的卫星恒星质量函数、平均 SFR 和淬灭分数，同时保持孤立的矮星大部分是恒星形成的。相对于孤立场星系，卫星中增强的猝灭导致该模型最大限度地依赖光晕组装来解释观察到的环境猝灭。将模型外推到 m_⋆ ∼ 10^6.5M_⊙ 得到的淬火分数为≳30%（对于在这个恒星质量的MW质量宿主的卫星）。光谱巡天很快就可以测试这一特定预测，以揭示内部反馈、质量和气体吸积停止、卫星特异性气体过程和再电离对微弱低质量星系演化的相对重要性。