Kinematics of disk galaxies in (proto-)clusters at z = 1.5
Kinematics of disk galaxies in (proto-)clusters at z = 1.5
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DOI：
10.1051/0004-6361/201935527
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发表时间：
2019-03
影响因子：
6.5
通讯作者：
A. Boehm;B. Ziegler;J. M. Pérez-Martínez;T. Kodama;M. Hayashi;C. Maier;M. Verdugo;Y. Koyama
中科院分区：
文献类型：
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作者：
A. Boehm;B. Ziegler;J. M. Pérez-Martínez;T. Kodama;M. Hayashi;C. Maier;M. Verdugo;Y. Koyama
目标。虽然在过去的几十年里，关于致密环境对红移低于单位的晚型星系的影响的许多方面已经被仔细研究过了，但关于z>；1的环境和盘状星系演化之间的相互作用的观测研究仍然很少。我们观测到了超级凸轮斯巴鲁战略计划中选择的z≈1.5处的恒星形成星系。这两个星系是通过窄带成像和灰色测光的光度红移确定的两个显著超密度的[O II]发射体的一部分。方法：研究方法。我们使用K波段多目标光谱仪对46个星系进行了H-α积分场光谱测量。电离气体图、恒星形成率和速度场是从Hα发射线得到的。我们量化了形态和运动学的不对称性，以寻找潜在的引力(例如，星系-星系)或流体动力学(例如，冲压)相互作用。结果。在我们的36个目标中检测到了Hα发射。在这些星系中，34个是z=1.47的两个(原始)星系团的成员，这证实了我们的选择策略是高效的。通过对模型速度场与观测速度场的拟合，确定了14个星系的内禀最大自转速度Vmax。利用光度-速度(Tully-Fisher)关系，我们发现这些星系在静止的B波段比其相似质量的局域对应星系亮度高达∼4mag。与z<；1处的场星系相比，z≈1.5(原星系)星系偏离局域Tully-Fisher关系的偏移量与它们的恒星形成率无关，而是与Vmax和气体速度弥散σg之比有关。这可能反映了较少的盘片已经稳定到纯粹的转动运动学和高的Vmax/σg比，正如在场中观察到的类似红移的情况一样。对退化的低红移星系团数据的测试表明，我们不能用目前的成像识别纯粹的流体动力学相互作用。由于(原)星系团的星系速度弥散相对较低(σv<；400 Km S−1)，引力相互作用可能更有效，导致比现在的星系团更高的运动不对称性。
Aims. While many aspects of the impact of dense environments on late-type galaxies at redshifts below unity have been scrutinized in the past few decades, observational studies of the interplay between environment and disk galaxy evolution at z > 1 are still scarce. We observed star-forming galaxies at z ≈ 1.5 selected from the HyperSuprimeCam Subaru Strategic Program. The galaxies are part of two significant overdensities of [O II] emitters identified via narrowband imaging and photometric redshifts from grizy photometry. Methods. We used the K-band Multi-Object Spectrograph (KMOS) to carry out Hα integral field spectroscopy of 46 galaxies in total. Ionized gas maps, star formation rates, and velocity fields were derived from the Hα emission line. We quantified morphological and kinematical asymmetries in order to look for potential gravitational (e.g., galaxy-galaxy) or hydrodynamical (e.g., ram-pressure) interactions. Results. Hα emission was detected in 36 of our targets. Of these galaxies, 34 are members of two (proto-)clusters at z = 1.47, confirming our selection strategy to be highly efficient. By fitting model velocity fields to the observed ones, we determined the intrinsic maximum rotation velocity Vmax of 14 galaxies. Utilizing the luminosity–velocity (Tully–Fisher) relation, we find that these galaxies are more luminous than their local counterparts of similar mass by up to ∼4 mag in the rest-frame B-band. In contrast to field galaxies at z < 1, the offsets of the z ≈ 1.5 (proto-)cluster galaxies from the local Tully–Fisher relation are not correlated with their star formation rates but with the ratio between Vmax and gas velocity dispersion σg. This probably reflects that fewer disks have settled to purely rotational kinematics and high Vmax/σg ratios, as is observed in the field at similar redshifts. Tests with degraded low-redshift cluster galaxy data show that we cannot identify purely hydrodynamical interactions with the imaging currently at hand. Due to relatively low galaxy velocity dispersions (σv < 400 km s−1) of the (proto-)clusters, gravitational interactions are likely more efficient, resulting in higher kinematical asymmetries than in present-days clusters.