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arXiv 2201.05162astro-ph.GAastro-ph.CO
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Local Group中棒材形成的数值模拟

Numerical simulations of bar formation in the Local Group

Ornela F. Marioni, Mario G. Abadi, Stefan Gottlöber, Gustavo Yepes

摘要:

超过50%的大质量盘状星系都有旋转的恒星棒。它们的形成和动力学已被广泛研究的数值和观测。虽然$Λ$ CDM宇宙学框架中的数值模拟预测了这种恒星成分的形成,但理论和观测结果之间似乎存在张力。模拟的条纹通常尺寸较大,并且具有比观察到的条纹更慢的图案速度。我们研究了棒星系的形成和演化,使用两个$Λ$ CDM放大的流体动力学模拟的CLUES项目,遵循宇宙学的本星系团样体积的演变。我们发现,我们的模拟酒吧,在$z = 0$,都是较短和较快的旋转比以前的宇宙学模拟研究中发现的缓解上述紧张局势。这些条与观察到的条长度分布的短尾端相匹配。与以前的数值计算结果一致,我们发现酒吧的形式在这些系统中,光盘的自引力是占主导地位的暗物质晕,使他们对酒吧的形成不稳定。我们的酒吧在过去的3-4 Gyr发展,直到他们达到目前的长度和强度;随着酒吧的增长,他们的长度增加,而他们的旋转速度下降。尽管这种减速,在红移$z = 0$,它们的旋转速度和大小与观测数据吻合得很好。

英文摘要:

More than 50 per cent of present-day massive disc galaxies show a rotating stellar bar. Their formation and dynamics have been widely studied both numerically and observationally. Although numerical simulations in the $Λ$CDM cosmological framework predict the formation of such stellar components, there seems to be a tension between theoretical and observational results. Simulated bars are typically larger in size and have slower pattern speed than observed ones. We study the formation and evolution of barred galaxies, using two $Λ$CDM zoom-in hydrodynamical simulations of the CLUES project that follow the evolution of a cosmological Local Group-like volume. We found that our simulated bars, at $z = 0$, are both shorter and faster rotators than previous ones found in other studies on cosmological simulations alleviating the tension mentioned above. These bars match the short tail-end of the observed bar length distribution. In agreement with previous numerical works, we find that bars form in those systems where the disc self-gravity is dominant over the dark matter halo, making them unstable against bar formation. Our bars developed in the last 3-4 Gyr until they achieve their current length and strength; as bars grow, their lengths increase while their rotation speeds decrease. Despite this slowdown, at redshift $z = 0$ their rotation speeds and size match well the observational data.

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