The MASSIVE Survey XIV—Stellar Velocity Profiles and Kinematic Misalignments from 200 pc to 20 kpc in Massive Early-type Galaxies
The MASSIVE Survey XIV—Stellar Velocity Profiles and Kinematic Misalignments from 200 pc to 20 kpc in Massive Early-type Galaxies
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DOI：
10.3847/1538-4357/ab7016
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
Irina Ene;Chung-Pei Ma;J. Walsh;J. Greene;Jens Thomas;J. Blakeslee
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文献类型：
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作者：
Irina Ene;Chung-Pei Ma;J. Walsh;J. Greene;Jens Thomas;J. Blakeslee
我们利用双子座积分场光谱仪（IFS）的高空间分辨率恒星速度图和麦克唐纳米切尔积分场光谱仪（IFS）的宽视场速度图，研究了在MASSIVE巡天中恒星质量为M* > 1011.7M⊙的20个早期型星系（ETGs）的恒星速度分布和运动学失调，从~ 200pc到~ 20kpc。虽然80%的星系在中心区域和主体区域都具有低自旋（λ < 0.1）和低旋转速度（<50 km s−1），但我们发现速度特征和不对准角的范围各不相同。在中心运动轴可测量的18个星系中，有10个星系的运动轴和光度长轴排列良好，其余8个星系的不对准角分布相当均匀，从15°到最大值为90°。中心运动偏差和星系自旋之间有很强的相关性，所有四个自旋显著的星系都有良好的运动轴和光度轴，但只有43%的低自旋星系是良好的。星系内的中心和主体运动轴并不总是对齐的。当两个运动轴对齐时（约60%的情况），它们要么也与光度长轴对齐，要么与其正交。我们发现13个星系也表现出明显的局部运动扭曲，一个星系有一个反向旋转的核心。可能需要一个多样化的组合历史，包括多种不同的祖质量比和轨道的多种气体贫合并，以解释低自旋的优势以及本文报道的本地大质量etg的中心和主体速度特征的广泛范围。
We use high spatial resolution stellar velocity maps from the Gemini integral-field spectrograph (IFS) and wide-field velocity maps from the McDonald Mitchell IFS to study the stellar velocity profiles and kinematic misalignments from ∼200 pc to ∼20 kpc in 20 early-type galaxies (ETGs) with stellar mass M* > 1011.7M⊙ in the MASSIVE survey. While 80% of the galaxies have low spins (λ < 0.1) and low rotational velocities (<50 km s−1) in both the central region and the main body, we find a diverse range of velocity features and misalignment angles. For the 18 galaxies with measurable central kinematic axes, 10 have well aligned kinematic axis and photometric major axis, and the other eight galaxies have misalignment angles that are distributed quite evenly from 15° to the maximal value of 90°. There is a strong correlation between central kinematic misalignment and galaxy spin, where all four galaxies with significant spins have well aligned kinematic and photometric axes, but only 43% of the low-spin galaxies are well aligned. The central and main-body kinematic axes within a galaxy are not always aligned. When the two kinematic axes are aligned (∼60% of the cases), they are either also aligned with the photometric major axis or orthogonal to it. We find 13 galaxies to also exhibit noticeable local kinematic twists, and one galaxy to have a counterrotating core. A diverse assembly history consisting of multiple gas-poor mergers of a variety of progenitor mass ratios and orbits is likely to be needed to account for the predominance of low spins and the wide range of central and main-body velocity features reported here for local massive ETGs.