The morphological classification of distant radio galaxies explored with three-dimensional simulations
The morphological classification of distant radio galaxies explored with three-dimensional simulations
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通过三维模拟探索遥远射电星系的形态分类
DOI：
10.1093/mnras/stz2525
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发表时间：
2019
影响因子：
4.8
通讯作者：
Justin Donohoe
中科院分区：
文献类型：
--
作者：
Michael D. Smith;Justin Donohoe
我们探索了对超音速喷流驱动的射电星系进行高分辨率三维模拟的大型系统研究的观测意义。在这个基准研究中，我们使用非相对论流体动力学绝热流动从喷嘴进入恒定压力匹配的环境。同步辐射发射率是通过注入材料的热压来近似计算的。我们发现，随着距离的增加(即观测分辨率的降低)和方向的减小，模拟射电星系的形态分类明显依赖于几个因素，这往往会导致从FR II(肢体变亮)到FR I(肢体变暗)类型的重新分类。我们引入了脑叶或肢体亮度指数(LBI)来更准确地测量无线电脑叶类型。喷流密度也如预期的那样具有影响，较低的密度导致更宽和桥接的波瓣形态以及更明亮的射电喷流。因此，将观测到的源类型与本征喷流动力学联系起来并不简单。喷流方向的进动也可能是LBI和FR级较低的宽弛豫源以及X形和双重结构的原因。螺旋结构不会产生，因为进动通常太慢。我们的结论是，由于合并相关的重定向和进动以及分辨率的限制，遥远的射电星系可能会出现系统性更多的边缘暗化。
We explore the observational implications of a large systematic study of high-resolution three-dimensional simulations of radio galaxies driven by supersonic jets. For this fiducial study, we employ non-relativistic hydrodynamic adiabatic flows from nozzles into a constant pressure-matched environment. Synchrotron emissivity is approximated via the thermal pressure of injected material. We find that the morphological classification of a simulated radio galaxy depends significantly on several factors with increasing distance (i.e. decreasing observed resolution) and decreasing orientation often causing reclassification from FR II (limb-brightened) to FR I (limb-darkened) type. We introduce the Lobe or Limb Brightening Index (LBI) to measure the radio lobe type more precisely. The jet density also has an influence as expected with lower density leading to broader and bridged lobe morphologies as well as brighter radio jets. Hence, relating observed source type to the intrinsic jet dynamics is not straightforward. Precession of the jet direction may also be responsible for wide relaxed sources with lower LBI and FR class as well as for X-shaped and double–double structures. Helical structures are not generated because the precession is usually too slow. We conclude that distant radio galaxies could appear systematically more limb darkened due to merger-related redirection and precession as well as due to the resolution limitation.
FR0 射电星系的高分辨率 VLA 观测：紧凑射电源的特性和性质
影响因子：
4.8
作者：
Baldi R
通讯作者：
Baldi R