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arXiv 0706.0093astro-ph
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潮汐矮星系的早期演化

The early evolution of tidal dwarf galaxies

S. Recchi, Ch. Theis, P. Kroupa, G. Hensler

摘要:

背景:矮星系可以从潮汐尾出现的自引力结构中产生。在本地宇宙中,有多少已知的矮星系可以有这样的起源仍然是一个争论的问题。目的:在我们努力理解潮汐矮星系的起源和演化以及它们与本地物体的对应关系时,第一步是了解这些星系(应该具有有限数量的暗物质)如何对正在进行的恒星形成的反馈做出反应。方法:利用二维化学动力学计算研究孤立的无暗物质矮星系的早期演化。我们提出的模型中,反馈参数是不同的。我们还将结果与暗物质主导的矮星系模型进行了比较。结果如下:所有考虑的模型表明,恒星形成的收益超过3亿年,因此,矮星系没有大的暗物质晕不一定很快被摧毁。这些天体的化学演化与本星系群dSphs的主要化学性质一致。具有大的暗物质晕的模型显示出与没有暗物质的模型一致的结果,表明在确定dSph-sized矮星系的全球行为时,气体的分布比势阱的深度更重要。

英文摘要:

Context: Dwarf galaxies can arise from self-gravitating structures emerging from tidal tails. What fraction of the known dwarf galaxies in the Local Universe can have this origin is still a matter of debate. Aims: In our effort to understand the origin and evolution of tidal dwarf galaxies and their correspondence with local objects, the first step is to understand how these galaxies (which are supposed to have a limited amount of dark matter) react to the feedback of the ongoing star formation. Methods: We make use of 2-D chemodynamical calculations in order to study the early evolution of isolated, dark matter-free dwarf galaxies. We present models in which feedback parameters are varied. We also compare the results with dark matter-dominated dwarf galaxy models. Results: All the considered models show that the star formation proceeds for more than 300 Myr, therefore dwarf galaxies without large dark matter halos are not necessarily quickly destroyed. The chemical evolution of these objects is consistent with the main chemical properties of the dSphs of the Local Group. Models with large dark matter halos show results consistent with models free of dark matter, indicating that the distribution of gas is more important than the depth of the potential well in determining the global behaviour of dSph-sized dwarf galaxies.

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