Using synchrotron emission modelling of relativistic hydrodynamic jet simulations to study the FR I/FR II dichotomy of active galactic nuclei radio jets
Using synchrotron emission modelling of relativistic hydrodynamic jet simulations to study the FR I/FR II dichotomy of active galactic nuclei radio jets
复制标题
使用相对论流体动力射流模拟的同步加速器发射模型研究活动星系核射电射流的 FR I/FR II 二分法
DOI：
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发表时间：
2019
影响因子：
4.8
通讯作者：
J. Beall
中科院分区：
文献类型：
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作者：
I. V. D. Westhuizen;B. V. Soelen;P. Meintjes;J. Beall
本文用三维相对论流体动力学方法对活动星系核喷流进行了数值模拟，研究了FR Ⅰ/FR Ⅱ二分法。提出了三个模拟，说明了高/低洛伦兹因子注入以及分层背景介质的形态差异。洛伦兹因子10和1.0014分别用于高洛伦兹因子和低洛伦兹因子情况。流体动力学模拟表明，在其初始注入光度的基础上的射流的形态划分。另外还建立了一个数值模拟，研究了在一定时间后降低质量注入时低洛仑兹因子射流的演化。一个同步辐射模型被应用到这些模拟再现强度地图在无线电频率（1.5GHz）的FR I/FR II射电星系的观测到的发射结构进行了比较。还研究了不同极角下多普勒增强对强度图的影响。的强度图的高和低洛伦兹因子的情况下再现的发射结构，类似于FR II型射电星系与一个占主导地位的茧区域包含时间依赖的热点和细丝。然而，如果在设定的时间段后降低质量注入速率，则对于低洛伦兹因子的情况产生FR I样结构。
In this paper three dimensional relativistic hydrodynamic simulations of AGN jets are presented to investigate the FR I/FR II dichotomy. Three simulations are presented which illustrates the difference in morphology for high/low Lorentz factor injection as well as a stratified background medium. Lorentz factors of 10 and 1.0014 were used for the high and low Lorentz factor cases respectively. The hydrodynamic simulations show a division in the morphology of jets based on their initial injection luminosity. An additional simulation was set up to investigate the evolution of the low Lorentz factor jet if the mass injection was lowered after a certain time. A synchrotron emission model was applied to these simulations to reproduce intensity maps at radio frequencies (1.5GHz) which were compared to the observed emission structures of FR I/FR II radio galaxies. The effect of Doppler boosting on the intensity maps was also investigated for different polar angles. The intensity maps of both the high and low Lorentz factor cases reproduced emission structures that resemble those of FR II type radio galaxies with a dominant cocoon region containing time dependent hot spots and filaments. An FR I like structure was, however, produced for the low Lorentz factor case if the mass injection rate was lowered after a set time period.