主要富气盘-盘合并后的结构、动力学和化学富集模式
Structure, Kinematics, and Chemical Enrichment Patterns after Major Gas-Rich Disc-Disc Mergers
摘要：
我们使用了N-体平滑粒子流体动力学算法，详细处理恒星形成，超新星反馈和化学富集，进行8个模拟气体丰富的盘星系之间的合并。我们改变的质量比的祖先，他们的旋转轴，和他们的轨道参数和分析的残余物的运动学，结构和化学性质。这些模拟结果中的六个合并残留物的形成与光盘形态作为一个结果的残留物的大气体部分。我们发现，恒星合并过程中形成（突然的星爆发生在我们的模拟和持续0.2-0.3 Gyr）和合并后形成的那些有不同的运动学和化学性质。第一类位于厚盘或晕中。它们部分受到速度弥散的支持，即使在金属丰度高达[Fe/H]=-0.5时也具有高[α/Fe]比。前者-年轻的组件-位于旋转支撑的薄圆盘中，并且具有较低的[α/Fe]比。这两个组件的旋转支持的差异导致厚盘的旋转滞后的薄盘的多达两个因素，最近observed.We发现，而合并残留的运动学和结构特性强烈依赖于合并的轨道参数，有一个显着的均匀性的合并的化学性质。这表明，可以得出关于富气合并的化学特征的一般结论。
英文摘要：
We used an N-body smoothed particle hydrodynamics algorithm, with a detailed treatment of star formation, supernovae feedback, and chemical enrichment, to perform eight simulations of mergers between gas-rich disc galaxies. We vary the mass ratio of the progenitors, their rotation axes, and their orbital parameters and analyze the kinematic, structural, and chemical properties of the remnants. Six of these simulations result in the formation of a merger remnant with a disc morphology as a result of the large gas-fraction of the remnants. We show that stars formed during the merger (a sudden starburst occur in our simulation and last for 0.2-0.3 Gyr) and those formed after the merger have different kinematical and chemical properties. The first ones are located in thick disc or the halo. They are partially supported by velocity dispersion and have high [alpha/Fe] ratios even at metallicities as high as [Fe/H]=-0.5. The former ones -- the young component -- are located in a thin disc rotationally supported and have lower [alpha/Fe] ratios. The difference in the rotational support of both components results in the rotation of the thick disc lagging that of the thin disc by as much as a factor of two, as recently observed.We find that, while the kinematic and structural properties of the merger remnant depends strongly upon the orbital parameters of the mergers, there is a remarkable uniformity in the chemical properties of the mergers. This suggests that general conclusions about the chemical signature of gas-rich mergers can be drawn.
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