具有长轴旋转的早型星系中普遍存在的相互作用迹象
Ubiquitous signs of interactions in early-type galaxies with prolate rotation
摘要：
一小部分早型星系（ETG）表现出长轴自转，也就是说，它们绕着光度长轴旋转。在模拟中，已知星系合并的某些配置会产生这种类型的旋转。我们调查的协会的长轴旋转和星系之间的相互作用的迹象观察星系。我们从文献中收集了19个具有明显长轴旋转的附近ETG样本，并检查了它们的地基深光学图像的相互作用迹象- 18个在档案图像中，一个在米兰科维奇望远镜获得的新图像中。潮汐尾，壳，不对称/扰动恒星晕，或正在进行的相互作用是目前在所有19个长转子。比较这与潮汐扰动的频率之间的一般样本的ETG大致相似的质量范围和表面亮度限制，我们估计，这样的观察的机会概率只有0.00087。我们还发现了一个显着过剩的扁长旋转，是托管多个恒星壳。可见的潮汐特征意味着一个相对较新的星系相互作用。这与Illustris大尺度宇宙流体动力学模拟一致，在过去的6 Gyr期间，在主要的合并中主要形成长轴旋转体。在附录中，我们介绍了另一个星系NGC 7052的性质，这是一个长轴旋转星系，没有深空图像，但HST图像显示存在一个突出的壳层，这在以前没有报道过。
英文摘要：
A small fraction of early-type galaxies (ETGs) show prolate rotation, i.e. they rotate around their long photometric axis. In simulations, certain configurations of galaxy mergers are known to produce this type of rotation. We investigate the association of prolate rotation and signs of galaxy interactions among the observed galaxies. We collected a sample of 19 nearby ETGs with distinct prolate rotation from the literature and inspected their ground-based deep optical images for interaction signs - 18 in archival images and one in a new image obtained with the Milanković telescope. Tidal tails, shells, asymmetric/disturbed stellar halos, or on-going interactions are present in all the 19 prolate rotators. Comparing this with the frequency of tidal disturbance among the general sample of ETGs of a roughly similar mass range and surface-brightness limit, we estimate that the chance probability of such an observation is only 0.00087. We also found a significant overabundance of prolate rotators that are hosting multiple stellar shells. The visible tidal features imply a relatively recent galaxy interaction. That agrees with the Illustris large-scale cosmological hydrodynamical simulation, where prolate rotators are predominantly formed in major mergers during the last 6 Gyr. In the appendix, we present the properties of an additional galaxy, NGC 7052, a prolate rotator for which no deep images are available, but for which an HST image revealed the presence of a prominent shell, which had not been reported before.
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