Investigating the spectral age problem with powerful radio galaxies
Investigating the spectral age problem with powerful radio galaxies
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研究强大射电星系的光谱年龄问题
DOI：
10.1093/mnras/stz3396
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发表时间：
2020
影响因子：
4.8
通讯作者：
Mahatma V
中科院分区：
文献类型：
--
作者：
Mahatma V
“光谱年龄问题”是我们在系统上无法将射电星系叶状体中辐射电子的最大冷却时间与由叶状体的动态演化所模拟的年龄相协调。虽然在产生两种年龄估计的模型中存在已知的不确定性，但相对于动态年龄，“光谱”年龄通常被低估了，因此导致对强大射电星系的时间平均动力学反馈的估计不可靠。在这项工作中，我们试图通过观测两个星团中心的强大射电星系来解决光谱年龄问题；3C 320和3C 444。利用高分辨率宽带Karl G. Jansky甚大阵列对射电源的观测和深xmm -牛顿望远镜和钱德拉望远镜对它们的热星团内介质的观测，结合分析模型的使用，我们可靠地确定了它们的光谱和动力学年龄。在找到符合我们观测约束的自洽动力学模型，并考虑到亚均分磁场后，我们发现我们的光谱年龄仍然被低估了至少两个因素。均分磁场会低估谱龄，误差可达20倍。射电叶中电子居群的湍流混合很可能是造成光谱年龄/动力学年龄差异的主要因素，必须在对强大射电星系的大样本研究中加以考虑。
The ‘spectral age problem’ is our systematic inability to reconcile the maximum cooling time of radiating electrons in the lobes of a radio galaxy with its age as modelled by the dynamical evolution of the lobes. While there are known uncertainties in the models that produce both age estimates, ‘spectral’ ages are commonly underestimated relative to dynamical ages, consequently leading to unreliable estimates of the time-averaged kinetic feedback of a powerful radio galaxy. In this work, we attempt to solve the spectral age problem by observing two cluster-centre powerful radio galaxies; 3C 320 and 3C 444. With high-resolution broad-band Karl G. Jansky Very Large Array observations of the radio sources and deepXMM–NewtonandChandraobservations of their hot intracluster media, coupled with the use of an analytic model, we robustly determine their spectral and dynamical ages. After finding self-consistent dynamical models that agree with our observational constraints, and accounting for sub-equipartition magnetic fields, we find that our spectral ages are still underestimated by a factor of two at least. Equipartition magnetic fields will underestimate the spectral age by factors of up to ∼20. The turbulent mixing of electron populations in the radio lobes is likely to be the main remaining factor in the spectral age/dynamical age discrepancy, and must be accounted for in the study of large samples of powerful radio galaxies.
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DOI：
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发表时间：
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发表时间：
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影响因子：
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发表时间：
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