标题： 星系形成模拟中棒状结构的宇宙演化 显示英文标题

标题： Cosmic evolution of bars in simulations of galaxy formation

摘要： 我们研究了在银河系质量星系形成中的完全自洽流体动力学模拟中形成的两个棒状结构的演化。 其中一个星系在 $z = 0$ 时具有更高的中心质量集中度，并且其棒状结构比另一个更长更强。 较强的棒状结构通过将其角动量主要传递给暗物质晕而演化。 因此，棒状结构的旋转速度随时间减少，而其振幅随时间增加。 这些特征定性地与理想化模拟的结果一致。 在早期演化阶段，较强棒状结构的图案速度在其半圈内上下波动。 这些振荡发生在棒状结构与 $m = 4$ 模式的傅里叶分量不对齐时。 这些振荡与暗物质晕的三轴性振荡相关，但不同于理想化模拟中所识别的方式。 尽管较弱的棒状结构的旋转速度随时间减慢，但其振幅并未增加。这一结果与理想化模拟的预期相矛盾，这是由于质量损失和恒星种群反馈导致的中心密度下降所致。 较弱棒状结构的振幅进一步因与盘中恒星团块相互作用而注入角动量而减弱。 在两个星系中，棒状结构都在 4:1 共振处终止。 显示英文摘要

摘要： We investigate the evolution of two bars formed in fully self-consistent hydrodynamic simulations of the formation of Milky Way-mass galaxies. One galaxy shows higher central mass concentration and has a longer and stronger bar than the other at $z = 0$. The stronger bar evolves by transferring its angular momentum mainly to the dark halo. Consequently the rotation speed of the bar decreases with time, while the amplitude of the bar increases with time. These features qualitatively agree with the results obtained by idealized simulations. The pattern speed of the stronger bar largely goes up and down within a half revolution in its early evolutionary stage. These oscillations occur when the bar is misaligned with the $m = 4$ mode Fourier component. These oscillations correlate with the oscillations in the triaxilality of the dark matter halo, but differently from the way identified by idealized simulations. The amplitude of the weaker bar does not increase despite the fact that its rotation slows down with time.This result contradicts what is expected from idealized simulations and is caused by the decline of the central density associated with the mass loss and feedback from the stellar populations. The amplitude of the weaker bar is further weakens by the angular momentum injection by the interactions with stellar clumps in the disk. In the both galaxies, the bars are terminated around the 4:1 resonance.