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arXiv 1507.04746astro-ph.GA
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从盘状星系到球状星系:合并对星系形态的影响

From Discs to Bulges: effect of mergers on the morphology of galaxies

Rahul Kannan, Andrea V. Maccio', Fabio Fontanot, Benjamin P. Moster, Wouter Karman, Rachel S. Somerville

摘要:

我们研究的合并对星系形态的影响,通过模拟合并树的方法首先提出的Moster等人。这种方法结合N体宇宙学模拟和半解析技术,以提取现实的初始条件星系合并。然后使用高分辨率的流体动力学模拟来演化这些,其中包括暗物质、恒星、盘中的冷气体和晕中的热气体。我们表明,卫星质量吸积是不像以前认为的那样有效,因为有大量的恒星剥离前的最后合并。即使在大合并的情况下,恒星盘质量转移到凸起的比例也很低,这主要是由于部分恒星盘质量分散到晕中。我们证实了霍普金斯等人的发现,富含气体的盘能够更有效地经受住主要的合并。与合并相关的增强的恒星形成并不局限于星系的凸出部分,但也有相当大的一部分发生在圆盘中。在星系模型中包含热气体库有助于降低核球形成的效率。总的来说,我们的研究结果表明,合并并不像以前认为的那样有效地将光盘转化为凸起。这可能解释了观测无凸星系和结构形成的分级方案之间的一些紧张关系。

英文摘要:

We study the effect of mergers on the morphology of galaxies by means of the simulated merger tree approach first proposed by Moster et al. This method combines N-body cosmological simulations and semi-analytic techniques to extract realistic initial conditions for galaxy mergers. These are then evolved using high resolution hydrodynamical simulations, which include dark matter, stars, cold gas in the disc and hot gas in the halo. We show that the satellite mass accretion is not as effective as previously thought, as there is substantial stellar stripping before the final merger. The fraction of stellar disc mass transferred to the bulge is quite low, even in the case of a major merger, mainly due to the dispersion of part of the stellar disc mass into the halo. We confirm the findings of Hopkins et al., that a gas rich disc is able to survive major mergers more efficiently. The enhanced star formation associated with the merger is not localised to the bulge of galaxy, but a substantial fraction takes place in the disc too. The inclusion of the hot gas reservoir in the galaxy model contributes to reducing the efficiency of bulge formation. Overall, our findings suggest that mergers are not as efficient as previously thought in transforming discs into bulges. This possibly alleviates some of the tensions between observations of bulgeless galaxies and the hierarchical scenario for structure formation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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