The inner structure of early-type galaxies in the Illustris simulation
The inner structure of early-type galaxies in the Illustris simulation
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DOI：
10.1093/mnras/stx899
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发表时间：
2016-10
影响因子：
4.8
通讯作者：
Dandan Xu;V. Springel;D. Sluse;P. Schneider;A. Sonnenfeld;D. Nelson;M. Vogelsberger;L. Hernquist
中科院分区：
文献类型：
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作者：
Dandan Xu;V. Springel;D. Sluse;P. Schneider;A. Sonnenfeld;D. Nelson;M. Vogelsberger;L. Hernquist
早型星系为冷暗物质宇宙学的预测和进入星系形成模型的重子物理假设提供了独特的检验。在这项工作中，我们使用的Illustris模拟研究的三个主要性质，即恒星轨道各向异性，中央暗物质的分数和中央径向密度斜率的相关性，以及它们的红移的演变，因为$z=1.0$。我们发现，较低质量的星系或星系在较高的红移往往是蓝色的休息帧的颜色，有较高的中心气体分数，并具有更多的切向各向异性轨道和陡峭的中心密度斜率比他们的高质量或低红移的同行，分别。在有效半径内的投影中心暗物质分数显示出非常温和的质量依赖性，但由于孔径效应与星系有效半径正相关。通过结合强透镜测量与单孔径运动学得到的中心密度斜率被发现不同于真实密度斜率。我们确定系统偏差在这种测量是由于两个常见的建模假设，各向同性恒星轨道分布和幂律密度分布。我们还比较了早期类型的星系的属性，从现有的星系和强透镜调查，我们发现在一般广泛的协议，但也有一些紧张局势，这构成了一个潜在的挑战，恒星形成和反馈模型所采用的模拟。
Early-type galaxies provide unique tests for the predictions of the cold dark matter cosmology and the baryonic physics assumptions entering models for galaxy formation. In this work, we use the Illustris simulation to study correlations of three main properties of early-type galaxies, namely, the stellar orbital anisotropies, the central dark matter fractions and the central radial density slopes, as well as their redshift evolution since $z=1.0$. We find that lower-mass galaxies or galaxies at higher redshift tend to be bluer in rest-frame colour, have higher central gas fractions, and feature more tangentially anisotropic orbits and steeper central density slopes than their higher-mass or lower-redshift counterparts, respectively. The projected central dark matter fraction within the effective radius shows a very mild mass dependence but positively correlates with galaxy effective radii due to the aperture effect. The central density slopes obtained by combining strong lensing measurements with single aperture kinematics are found to differ from the true density slopes. We identify systematic biases in this measurement to be due to two common modelling assumptions, isotropic stellar orbital distributions and power-law density profiles. We also compare the properties of early-type galaxies in Illustris to those from existing galaxy and strong lensing surveys, we find in general broad agreement but also some tension, which poses a potential challenge to the stellar formation and feedback models adopted by the simulation.