The ATLAS3D project - XXV. Two-dimensional kinematic analysis of simulated galaxies and the cosmological origin of fast and slow rotators
The ATLAS3D project - XXV. Two-dimensional kinematic analysis of simulated galaxies and the cosmological origin of fast and slow rotators
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DOI：
10.1093/mnras/stt1919
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发表时间：
2014-11-11
影响因子：
4.8
通讯作者：
Young, L. M.
中科院分区：
文献类型：
--
作者：
Naab, Thorsten;Oser, L.;Young, L. M.
我们对单个中心星系的 44 个宇宙流体动力学模拟样本进行了详细的二维恒星动力学分析，其中恒星质量为 2 x 10(10) M 圆点小于或相似于 M-* 小于或相似于 6 x 10(11) M 圆点。为每个中心星系和最大质量的卫星构建了恒星视线速度、速度色散和高阶高斯-埃尔米特矩 h(3) 和 h(4) 的运动学图。使用 lambda(R) 参数对旋转量进行量化。模拟星系的速度、速度色散、h(3) 和 h(4) 场显示出与 ATLAS(3D) 巡天中观测到的早期型星系运动图类似的多样性。这包括快速（规则）、慢速和错位旋转、具有嵌入式冷盘组件的热球体以及具有反向旋转核心或速度色散中心凹陷的星系。我们将当今的运动学特性与星系的个体宇宙学形成历史联系起来。一般来说，主要星系合并对旋转特性有重大影响，导致合并残余物的旋转下降和旋转上升。自 z 接近 2 以来，具有显着（大于或相似于 18%）恒星原位形成的较低质量星系，或者在其形成历史中具有额外的富含气体的主要合并（导致旋转上升），形成细长的（ε 类似于 0.45）快速旋转体（lambda(R) 类似于 0.46），具有 h(3) 和 nu/sigma 的明显反相关性。快速旋转子的另一个形成路径包括导致残余物旋转的贫气主要合并（lambda(R) 类似于 0.43）。该形成路径不会导致反相关的 h(3) 和 nu/sigma。慢速旋转者的形成历史可能包括后期的重大合并。如果合并富含气体，则残余物通常是不太平坦的慢速旋转体，其速度分散的中心凹陷。如果合并气体贫乏，则残余物会非常拉长（epsilon 类似于 0.43）并且缓慢旋转（lambda(R) 类似于 0.11）。与罕见的非旋转圆形早期型星系最一致的星系仅通过贫气体的小合并而生长。一般来说，质量越大的星系，原位恒星形成越少，因为 z 类似于 2，旋转速度较慢，并且恒星种群较老。我们讨论快速和缓慢旋转星系形成的一般含义以及基础模型的弱点和优点。
We present a detailed two-dimensional stellar dynamical analysis of a sample of 44 cosmological hydrodynamical simulations of individual central galaxies with stellar masses of 2 x 10(10) M-circle dot less than or similar to M-* less than or similar to 6 x 10(11) M-circle dot. Kinematic maps of the stellar line-of-sight velocity, velocity dispersion and higher order Gauss-Hermite moments h(3) and h(4) are constructed for each central galaxy and for the most massive satellites. The amount of rotation is quantified using the lambda(R)-parameter. The velocity, velocity dispersion, h(3) and h(4) fields of the simulated galaxies show a diversity similar to observed kinematic maps of early-type galaxies in the ATLAS(3D) survey. This includes fast (regular), slow and misaligned rotation, hot spheroids with embedded cold disc components as well as galaxies with counter-rotating cores or central depressions in the velocity dispersion. We link the present-day kinematic properties to the individual cosmological formation histories of the galaxies. In general, major galaxy mergers have a significant influence on the rotation properties resulting in both a spin-down as well as a spin-up of the merger remnant. Lower mass galaxies with significant (greater than or similar to 18 per cent) in situ formation of stars since z approximate to 2, or with additional gas-rich major mergers - resulting in a spin-up - in their formation history, form elongated (epsilon similar to 0.45) fast rotators (lambda(R) similar to 0.46) with a clear anticorrelation of h(3) and nu/sigma. An additional formation path for fast rotators includes gas-poor major mergers leading to a spin-up of the remnants (lambda(R) similar to 0.43). This formation path does not result in anticorrelated h(3) and nu/sigma. The formation histories of slow rotators can include late major mergers. If the merger is gas rich, the remnant typically is a less flattened slow rotator with a central dip in the velocity dispersion. If the merger is gas poor, the remnant is very elongated (epsilon similar to 0.43) and slowly rotating (lambda(R) similar to 0.11). The galaxies most consistent with the rare class of non-rotating round early-type galaxies grow by gas-poor minor mergers alone. In general, more massive galaxies have less in situ star formation since z similar to 2, rotate slower and have older stellar populations. We discuss general implications for the formation of fast and slowly rotating galaxies as well as the weaknesses and strengths of the underlying models.