蝌蚪星系在中等红移 $z \sim 0.4 - 1.5$ 下的运动学
The kinematics of tadpole galaxies at intermediate redshift $z \sim 0.4 - 1.5$
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中文总结 AI 辅助
本研究利用VLT/MUSE和HST/JWST数据，分析20个红移0.4-1.5的蝌蚪星系的电离气体运动学，发现多数星系保留有序运动，表明形态不对称不必然导致动力学无序，可能代表形态-运动学安定化的瞬态阶段。
中文摘要 AI 辅助
星系形态与运动学编码了关于星系组装历史的互补信息，但二者同步演化的程度仍不清楚。蝌蚪星系以其独特的头尾形态和显著的不对称性为特征，为研究强不对称星系是否能表现出有序的星系尺度运动学提供了理想的实验室。在本工作中，我们利用甚大望远镜/MUSE的深光谱以及哈勃空间望远镜和詹姆斯·韦伯空间望远镜的成像，对哈勃超深场中红移 $z=0.4 - 1.5$ 的20个形态选择的蝌蚪星系进行了电离气体运动学的详细分析。在20个星系中，有13个星系的由MUSE [O\\,{\sc ii}] $\lambda\lambda3726,3729$ 发射线导出的二维速度图显示出有序运动的证据，其特征是沿运动学主轴存在中等速度梯度，而其余系统则没有清晰的星系尺度有序运动学证据。在16个星系中，[O\\,{\sc ii}] 和静止系光学发射（由HST/F775W探测）的质心在空间上重合，投影偏移小于2千秒差距。形态-运动学位置角也总体对齐良好，中位错位角 $\Delta{\rm PA}\sim12^{\circ}$。尽管蝌蚪形态强不对称，这些结果表明这些系统中相当大比例保留了连贯的星系尺度气体运动学，暗示形态不对称不一定意味着全局无序的动力学状态。综合来看，我们的分析表明形态和运动学的安定化并非同时发生，这些蝌蚪星系可能代表了朝向形态-运动学联合安定化过程的瞬态演化阶段。
英文摘要
Galaxy morphology and kinematics encode complementary information about the assembly history of galaxies, but the extent to which they evolve in tandem remains unclear. Tadpole galaxies, characterized by their distinct head-tail morphology and pronounced asymmetry, provide an ideal laboratory for investigating whether strongly asymmetric galaxies can exhibit ordered galaxy-scale kinematics. In this work, we present a detailed analysis of the ionized-gas kinematics of 20 morphologically selected tadpole galaxies at redshifts $z=0.4 - 1.5$ in the Hubble Ultra Deep Field, using deep VLT/MUSE spectroscopy together with HST and JWST imaging. In 13 out of 20 galaxies, the 2D velocity maps derived from the MUSE [O\,{\sc ii}] $λ\lambda3726,3729$ emission show evidence for ordered motion, characterized by moderate velocity gradients along the kinematic major axis, while the remaining systems show no clear evidence for galaxy-scale ordered kinematics. In 16 galaxies, the [O\,{\sc ii}] and rest-frame optical emission, probed by HST/F775W, have spatially coincident centroids, with projected offsets of $<2$~kpc. The morpho-kinematic position angles are also generally well aligned, with a median misalignment of $Δ{\rm PA}\sim12^{\circ}$. Despite the strongly asymmetric tadpole morphologies, these results indicate that a substantial fraction of these systems retain coherent galaxy-scale gaseous kinematics, suggesting that morphological asymmetry need not imply a globally disordered dynamical state. Together, our analyses suggest that morphological and kinematic settlement does not occur simultaneously and these tadpole galaxies might represent a transient evolutionary phase towards the combined morpho-kinematic settlement process.
发表机构
- Inter-University Centre for Astronomy and Astrophysics（大学间天文学与天体物理中心）
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