Probing galaxy formation in the local universe: dwarf irregular galaxies and their globular cluster systems as galactic building blocks

星系的组装历史仍然是当今天体物理学中最迫切需要解决的问题之一。在目前流行的分级合并方案中，大质量星系被认为是通过大量合并而增长的。矮小不规则星系(DIRR)被广泛认为与它们的银河系前积木最相似。因此，研究DIRR星系中的古老球状星团(GC)(其性质反映了其早期形成时的物理条件)并与大质量星系中的GCS进行比较，可以用来量化DIRR星系对大质量现今星系及其球状星系团(GCS)组装的贡献。需要这样研究的一个很好的例子是我们银河系的GCS，因为它被发现拥有一个GC的亚群，其性质(颜色、亮度、水平分支形态、结构参数和轨道运动学)表明它们可能是在低质量卫星上形成的，后来被并入银河系GCS。该项目的目标是研究DLR星系中的GC的性质。这将允许1)限制DLR对大质量星系中GCS组装的贡献；2)探索我们银河系中化学上特殊的GC的起源；3)调查贫金属GC之间令人费解的质量-金属关系；4)评估DLR中GC的水平分支形态。因此，需要为实现研究计划的科学目标提供支持。波恩大学阿格兰德天文学研究所(阿尔法)的高水平和多样性天文研究将为这一项目提供良好的环境。

The assembly history of galaxies remains one of the most pressing questions in astrophysics to be solved today. In the currently popular hierarchical merging scenario, massive galaxies are believed to grow via numerous mergers. Dwarf irregular (dIrr) galaxies are widely regarded as being closest in resemblence to their pre-galactic building blocks. Hence, a study of the old globular clusters (GCs) in dIrr galaxies (whose properties reflect the physical conditions at the time of their early formation) and a comparison with GCs in massive galaxies can be used to quantify the contribution of dlrr galaxies to the assembly of massive present-day galaxies and their globular cluster systems (GCS). An excellent example for the need of such a study is the GCS of our Galaxy, because it is found to harbor a sub-population of GCs whose properties (colors, luminosities, horizontal branch morphologies, structural parameters and orbital kinematics) suggest that they might have formed in low-mass satellites and were later incorporated into the Milky Way GCS.The goal of the project is to investigate the properties of GCs in dlrr galaxies. This will allow to 1) constrain the contribution of dlrrs to the assembly of GCSs in massive galaxies; 2) probe the origin of chemically peculiar GCs in our Galaxy; 3) investigate the puzzling mass-metallicity relation among metal-poor GCs; 4) assess horizontal branch morphologies for GCs in dlrrs.Here support to achieve the science goals of the research programme is requested. The high level and diversity of astronomical research at the Argelander Institut für Astronomie (AlfA) of the University of Bonn will provide an excellent environment for this project.