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arXiv 1503.01117astro-ph.GAastro-ph.CO
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星系Angular Momentum在Illustris模拟:反馈和哈勃序列

Galactic Angular Momentum in the Illustris Simulation: Feedback and the Hubble Sequence

Shy Genel, S. Michael Fall, Lars Hernquist, Mark Vogelsberger, Gregory F. Snyder, Vicente Rodriguez-Gomez, Debora Sijacki, Volker Springel

摘要:

我们研究了数以千计的星系的恒星角动量的插图宇宙学模拟,捕捉星系内的引力和气体动力学,以及从恒星和黑洞的反馈。我们发现,模拟星系的角动量与观测结果相匹配,特别是晚型与早型星系有两种不同的关系。晚型星系的关系对应于宇宙学潮汐力矩产生的特定角动量完全守恒的预期值。早型星系的关系对应的保留只有~30%,但我们发现,这些早型星系与低角动量在z=0,但居住在高红移的晚型关系。其中一些在主要合并过程中突然失去角动量。为了获得进一步的了解,我们探索的缩放关系,在模拟中的星系形成物理修改相对于基准模型。我们发现,具有高质量负载因子的星系风是获得晚型星系典型的高角动量关系所必不可少的,而活动星系核的反馈主要是在相反的方向操作。因此,反馈控制星系的恒星角动量,似乎是建立哈勃序列的工具。

英文摘要:

We study the stellar angular momentum of thousands of galaxies in the Illustris cosmological simulation, which captures gravitational and gas dynamics within galaxies, as well as feedback from stars and black holes. We find that the angular momentum of the simulated galaxies matches observations well, and in particular two distinct relations are found for late-type versus early-type galaxies. The relation for late-type galaxies corresponds to the value expected from full conservation of the specific angular momentum generated by cosmological tidal torques. The relation for early-type galaxies corresponds to retention of only ~30% of that, but we find that those early-type galaxies with low angular momentum at z=0 nevertheless reside at high redshift on the late-type relation. Some of them abruptly lose angular momentum during major mergers. To gain further insight, we explore the scaling relations in simulations where the galaxy formation physics is modified with respect to the fiducial model. We find that galactic winds with high mass-loading factors are essential for obtaining the high angular momentum relation typical for late-type galaxies, while AGN feedback largely operates in the opposite direction. Hence, feedback controls the stellar angular momentum of galaxies, and appears to be instrumental for establishing the Hubble sequence.

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