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arXiv 2308.15134astro-ph.GA
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IC 1553中存在大尺度偏心星系外流及其与盘外弥散电离气体关联的证据

Evidence for a large off-centered galactic outflow and its connection to the extraplanar diffuse ionized gas in IC 1553

Lukas Dirks, Ralf-Jürgen Dettmar, Dominik J. Bomans, Peter Kamphuis, Ulrich Schilling

AI总结:

本研究通过MUSE积分场光谱分析侧向星系IC 1553的eDIG,发现存在偏心大尺度星系外流,揭示激波电离的重要贡献及星团分布对电离条件的影响,强调积分场观测对eDIG研究的关键作用。

摘要:

目的:我们分析了恒星形成侧向星系IC 1553的MUSE光学积分场光谱,以研究其盘外弥散电离气体(extraplanar diffuse ionized gas,简称eDIG)以及塑造其盘-晕界面的过程。方法:我们从积分场光谱中提取了光学发射线特征,并生成了常用的发射线诊断图,以分析eDIG的电离条件和分布。此外,我们还进行了引力势拟合,以研究疑似星系外流的运动学特征。结果:我们发现eDIG的标高最大值约为1.0千秒差距(kpc),且随投影方向上到星系中心的径向距离大致呈线性减小。eDIG的电离状态与纯光致电离情景不符,反而需要激波电离的显著贡献。这一点加上气体运动学特征,强烈表明存在一个星系尺度的外流,其起源位置距离星系中心至少1.4 kpc。eDIG中推断出的约225 km s⁻¹的激波速度,与我们通过势场建模估算的逃逸速度相当。当前正在形成恒星的星团的不对称分布,在eDIG中产生了一系列不同的电离条件。因此,垂直发射线轮廓沿星系长轴在定量和定性上均存在差异。本分析表明,在eDIG研究中,使用能兼顾空间和运动学分布的观测(例如利用积分场单元开展的观测)对于准确构建相关物理性质的图景至关重要。

英文摘要:

Aims. We analyze a MUSE optical integral field spectrum of the star-forming edge-on galaxy IC 1553 in order to study its extraplanar diffuse ionized gas (eDIG) and the processes shaping its disk-halo interface. Methods. We extracted the optical emission line properties from the integral field spectrum and generated the commonly used emission line diagnostic diagrams in order to analyze the ionization conditions and the distribution of the eDIG. Furthermore, we performed gravitational potential fitting to investigate the kinematics of a suspected galactic outflow. Results. We find that the eDIG scale height has a maximum value of approximately 1.0 kpc and decreases roughly linearly with the radial distance from the galactic center in projection. The ionization state of the eDIG is not consistent with a pure photoionization scenario and instead requires a significant contribution from shock ionization. This, in addition to the gas kinematics, strongly suggests the presence of a galactic scale outflow, the origin of which lies at least 1.4 kpc away from the galactic center. The inferred shock velocity in the eDIG of approximately 225 km s-1 is comparable to the escape velocity estimated from our potential modelling. The asymmetric distribution of currently star-forming clusters produces a range of different ionization conditions in the eDIG. As a result, the vertical emission line profiles vary quantitatively and qualitatively along the major axis of the galaxy. This analysis illustrates that it is crucial in studies of the eDIG to use observations that take the spatial and kinematical distributions into account, such as those done with integral field units, to form an accurate picture of the relevant physical properties.

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