The importance of binary systems for stellar population studies of early-type galaxies

早期型星系是我们详细了解当地宇宙中星系复杂的恒星形成和质量组装历史的关键基准。然而，允许我们追踪这些历史的恒星人口综合模型，从根本上受到其输入物理的限制。特别是，很少（如果有的话）人口综合模型包括大量双星的潜在重要影响。在这里，分别由博士领导的相关研究小组。李中木（中国）和Thorsten Lisker（德国）建议通过适当考虑双星系统的观测特性及其相互作用来扩展我们最先进的模型集，从而形成一个新的、最先进的单星+双星人口综合模型，该模型将向公众开放。然后，我们将把这个显著改进的模型应用于精心挑选的具有代表性的早期型矮星系和巨型星系样本，以便详细研究它们的恒星种群。这将是获得关于它们的恒星形成和质量聚集历史的可靠和结论性结果的重要一步，特别是这些与星系质量和环境密度的相关性。因此，我们的研究直接旨在显著提高我们对控制星系形成和演化的物理过程的理解。该项目将建立在中德研究小组富有成效的合作基础上。项目将在2年内完成，预计在国际知名同行评议期刊上发表3篇以上的科学论文。这将有利于中德两国的天体物理学研究，并将促进中德两国科学家在天文学和天体物理学领域的研究交流。

Early-type galaxies are crucial benchmarks for our detailed understanding of the complex star-formation and mass-assembly histories of galaxies in the local Universe. Stellar population synthesis models allowing us to trace these histories are, however, fundamentally limited by their input physics. Particularly, very few (if any) population synthesis models include the potentially important effects of large numbers of binary stars. Here, the associated research groups leaded respectively by Drs. Zhongmu Li (PR. China) and Thorsten Lisker (Germany) propose to expand our state-of-the-art model suite by properly accounting for the observational properties of binary systems and their interactions, leading to a new, state-of-the-art composite single+binary-star population synthesis model, which will be made publicly available. We will then apply this significantly improved model to carefully chosen samples of representative early-type dwarf and giant galaxies, in order to investigate their stellar populations in detail. This will be a major step forward in obtaining robust and conclusive results regarding their star formation and mass assembly histories, and in particular the correlation of these with galaxy mass and environmental density. Our study thus directly aims at significantly improving our understanding of the physical processes governing the formation and evolution of galaxies. The project will be founded on the fruitful cooperation of the Chinese and German research groups. It will finish in 2 years, and we foresee that 3 or more scientific publications will be submitted to internationally renowned peer-review journals. It will give benefit to the astrophysical researches of both China and Germany, and will improve the research communications between Chinese and German scientists in the field of astronomy and astrophysics.