ATLAS3D项目- II。早型星系的形态、运动学特征和光度轴与运动轴的对准
The ATLAS3D project - II. Morphologies, kinemetric features and alignment between photometric and kinematic axes of early-type galaxies
摘要：
[摘要]我们使用ATLAS 3D样本的260早型星系（ETG）来研究明显的运动失调角，Psi，定义为光度和运动主轴之间的角度。我们发现，71%的附近ETG是严格排列的系统（Psi > 5度），另外14%的星系5 < Psi < 10度，90%的星系Psi < 15度。考虑到测量的不确定性，90%的星系可以被认为是对准好于5度，这表明只有一小部分早型星系（约10%）在投影的半光半径内不符合轴对称。我们确定了形态特征，如酒吧和戒指（30%），尘埃结构（16%），蓝色核颜色（6%）和相互作用的证据（8%）。我们使用kinemetry分析的平均速度地图和两个广泛类型的定期和不定期的旋转分离的星系。我们发现了82%的规则旋转和17%的非规则旋转，由于数据质量，我们无法对2个星系进行分类。非规则旋转体通常存在于密集区域，并且质量很大。大多数星系没有任何特定的运动学特征，但我们在这里强调运动学上不同的核心（7%）和速度色散图中对齐的双峰（4%）的频率。大多数未对准的星系都有复杂的运动学，并且是不规则的旋转体。虽然趋势很弱，但有一种趋势是，在中等环境密度的星系和样本中质量最大的星系中发现了大的Psi值。我们认为，最常见的形成机制ETGs保留磁盘祖细胞的轴对称。不太常见的是，形成过程会导致一个净角动量低得多的三轴星系。
英文摘要：
[Abridged] We use the ATLAS3D sample of 260 early-type galaxies (ETGs) to study the apparent kinematic misalignment angle, Psi, defined as the angle between the photometric and kinematic major axis. We find that 71% of nearby ETGs are strictly aligned systems (Psi > 5 deg), an additional 14% have 5 < Psi < 10 deg and 90% of galaxies have Psi < 15 deg. Taking into account measurement uncertainties, 90% of galaxies can be considered aligned to better than 5 deg, suggesting that only a small fraction of early-type galaxies (~10%) are not consistent with axisymmetry within the projected half-light radius. We identify morphological features such as bars and rings (30%), dust structures (16%), blue nuclear colours (6%) and evidence of interactions (8%). We use kinemetry to analyse the mean velocity maps and separate galaxies in two broad types of regular and non-regular rotators. We find 82% of regular rotators and 17% non-regular rotators, with 2 galaxies that we were not able to classify due to data quality. The non-regular rotators are typically found in dense regions and are massive. The majority of galaxies do not have any specific kinemetric features, but we highlight here the frequency of the kinematically distinct cores (7%) and the aligned double peaks in the velocity dispersion maps (4%). Most of the galaxies that are misaligned have complex kinematics and are non-regular rotators. While the trends are weak, there is a tendency that large values of Psi are found in galaxies at intermediate environmental densities and among the most massive galaxies in the sample. We suggest that the most common formation mechanism for ETGs preserves the axisymmetry of the disk progenitors. Less commonly, the formation process results in a triaxial galaxy with much lower net angular momentum.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
