AI 中文总结
研究在宇宙学模拟中，对红移约4.5时银河系质量星系前身的大质量星系合并进行比较，用九个采用不同恒星反馈方案的代码，发现恒星形成率演化受反馈类型影响，还观察到相关关系，突出了模拟星系合并恒星形成响应对反馈规定的敏感性。
AI 中文摘要
由于星系合并具有高度非线性动力学和对初始条件的敏感性，是进行模拟代码比较的一个有吸引力的领域。我们在一个银河系质量星系前身的宇宙学放大流体动力学模拟中，对红移约为4.5时的一次大质量星系合并进行了比较研究。该比较采用了AGORA CosmoRun套件中的九个经过良好校准的、最先进的数值代码，每个代码采用不同的恒星反馈方案。我们发现，相互作用期间恒星形成率（SFR）的演化受恒星反馈类型的强烈影响。在反馈模型中使用动力学反馈会引发明显的合并诱导星暴，在合并前就开始减弱；使用无动力学反馈的热反馈即使在合并后也会使SFR持续增长；使用延迟冷却或辐射压力会导致SFR高度波动。在基于粒子的代码中追踪气体粒子表明，动力学反馈促进了在第一次近心点和远心点之间气体从次要星系流入主要星系，从而产生更早、更突出的星暴。相比之下，由超泡或延迟冷却反馈增强的热反馈会抑制气体冷却，产生更扩展的气体分布，并在合并期间阻碍强烈星暴。我们还观察到爆发分数与合并前气体分数之间存在与反馈模型无关的反相关关系。总体而言，这些结果突出了模拟星系合并中恒星形成响应对恒星反馈规定的敏感性。这项研究表明，星系合并可能是宇宙学模拟中恒星反馈过程的一个良好测试平台。
英文摘要
Given their highly nonlinear dynamics and sensitivity to initial conditions, galaxy mergers are a compelling area to conduct a simulation code comparison. We perform a comparative study of a major galaxy merger at $z \approx 4.5$ in cosmological zoom-in hydrodynamic simulations of a Milky Way-mass galaxy progenitor. The comparison employs the AGORA CosmoRun suite of nine well-calibrated, state-of-the-art numerical codes, each adopting a different stellar feedback scheme. We find that the evolution of the star formation rate (SFR) during the interaction is strongly shaped by the stellar feedback type. Using kinetic feedback in the feedback model drives a pronounced merger-induced starburst that starts to subside before coalescence; using thermal feedback without kinetic feedback yields prolonged SFR growth even after coalescence; and using delayed cooling or radiation pressure results in highly fluctuating SFR. Tracking gas particles in particle-based codes reveals that kinetic feedback facilitates gas inflow from the secondary galaxy onto the primary galaxy between the first periapsis and apoapsis, thus producing an earlier and more prominent starburst. In contrast, thermal feedback, augmented by superbubble or delayed-cooling feedback, suppresses gas cooling, creates a more extended gas distribution, and hinders strong starbursts during the merger. We also observe an inverse correlation between burst fraction and pre-merger gas fraction that is independent of feedback models. Overall, these results highlight the sensitivity of simulated galaxy mergers' star formation response to stellar feedback prescriptions. This study indicates that galaxy mergers may serve as a good testbed for stellar feedback processes in cosmological simulations.
Comments32 pages (24 pages main text plus appendices and references), 16 figures (11 in main text), 3 tables, submitted to MNRAS. Visit the AGORA Collaboration website (https://sites.google.com/site/santacruzcomparisonproject/) for more information
