Turbulence in the tail of a jellyfish galaxy
Turbulence in the tail of a jellyfish galaxy
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水母星系尾部的湍流
DOI：
10.1093/mnras/stad874
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发表时间：
2023
影响因子：
4.8
通讯作者：
Jáchym, Pavel
中科院分区：
文献类型：
--
作者：
Li, Yuan;Luo, Rongxin;Fossati, Matteo;Sun, Ming;Jáchym, Pavel
当星系通过星系团内部的团内介质（ICM）时，ICM的冲压压力可以从星系中剥离气体。汽提后的气体在尾侧形成尾部。这些星系因此被称为“水母星系”。ESO 137-001是一个典型的水母星系，位于最近的富星系团诺玛星系团。它壮观的多相尾巴具有复杂的形态和运动学，既来自印记星系的星际介质（ISM），也是剥离气体与周围热等离子体之间相互作用的结果，由辐射冷却和磁场介导。我们研究的运动学的多相尾巴使用高分辨率观测的电离和分子气体在整个结构。我们计算了沿着尾部移动标架中的速度结构函数，发现由Kelvin-Helmholtz（KH）不稳定性驱动的湍流迅速地使原来的ISM湍流趋于稳定，并在1030 kpc处达到饱和。也有一个暗示，尾部的远端可能已经开始继承可能由结构形成引起的预先存在的大规模ICM湍流。由分子气体测得的湍流一般与尾部电离气体测得的湍流一致，但振幅略低。大多数测得的湍流都低于热ICM的平均自由程（1011 kpc）。使用温/冷气体作为热ICM的示踪剂，我们发现，热等离子体的各向同性粘度必须抑制在0.01%斯皮策水平以下。
When galaxies move through the intracluster medium (ICM) inside galaxy clusters, the ram pressure of the ICM can strip the gas from galaxies. The stripped gas forms tails on the trailing side. These galaxies are hence dubbed ‘jellyfish galaxies’. ESO 137-001 is a quintessential jellyfish galaxy located in the nearest rich cluster, the Norma cluster. Its spectacular multiphase tail has complex morphology and kinematics both from the imprinted galaxy’s interstellar medium (ISM) and as a result of the interactions between the stripped gas and the surrounding hot plasma, mediated by radiative cooling and magnetic fields. We study the kinematics of the multiphase tail using high-resolution observations of the ionized and the molecular gas in the entire structure. We calculate the velocity structure functions in moving frames along the tail and find that turbulence driven by Kelvin–Helmholtz (KH) instability quickly overwhelms the original ISM turbulence and saturates at ∼30 kpc. There is also a hint that the far end of the tail has possibly started to inherit pre-existing large-scale ICM turbulence likely caused by structure formation. Turbulence measured by the molecular gas is generally consistent with that measured by the ionized gas in the tail but has a slightly lower amplitude. Most of the measured turbulence is below the mean free path of the hot ICM (∼11 kpc). Using warm/cool gas as a tracer of the hot ICM, we find that the isotropic viscosity of the hot plasma must be suppressed below 0.01 per cent Spitzer level.