Radiative properties of reconnection‐powered minijets in blazars
Radiative properties of reconnection‐powered minijets in blazars
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DOI：
10.1111/j.1365-2966.2010.18140.x
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发表时间：
2010-07
影响因子：
4.8
通讯作者：
K. Nalewajko;D. Giannios;M. Begelman;D. Uzdensky;M. Sikora
中科院分区：
文献类型：
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作者：
K. Nalewajko;D. Giannios;M. Begelman;D. Uzdensky;M. Sikora
我们建立了一个数值模型的发射从微型喷流，磁重联内部坡印廷通量主导的喷流驱动的本地化流提出解释的超快变化的耀变体。该模型的几何结构由两个楔形区域的相对论流动的气体，分离的一个固定的冲击。动力学的基础上的解决方案的相对论磁场重联与引导场从Lyubarsky。选择每个区域中的电子分布以匹配局部等离子体的压力和密度。从这两个地区的同步辐射被用来计算康普顿散射，康普顿阻力和光子光子不透明度的影响，精确治疗的各向异性和克莱因-西科政权。考虑了等离子体的辐射效应，包括压力对电子辐射损失的依赖性以及康普顿阻力下减速流动的绝热加热。结果被应用于2006年7月BL Lac天体PKS 2155−304的耀斑，目的是将高能立体系统（HESS）测量的TeV通量与满足可变性约束的模型相匹配，同时保持X射线辐射低于同时钱德拉观测。我们发现，孤立的微型射流与一个显着的引导字段的模型过度产生X射线发射，我们必须考虑到相反取向的微型射流的辐射相互作用，以实现足够高的康普顿TeV辐射的优势。我们认为，这种相互作用很可能发生在喷流中，有大量的内部重连，产生大量的错位的微型喷流。最后，我们表明，大喷流磁化确实需要满足所有的观测约束，有效的洛伦兹因子的微型射流等离子体必须大于50，与早期的一个区域的估计。
We construct a numerical model of emission from minijets, localized flows driven by magnetic reconnection inside Poynting-flux-dominated jets proposed to explain the ultrafast variability of blazars. The geometrical structure of the model consists of two wedge-like regions of relativistically flowing gas, separated by a stationary shock. The dynamics is based on solutions of relativistic magnetic reconnection with a guide field from Lyubarsky. Electron distributions in each region are chosen to match the pressure and density of the local plasma. Synchrotron emission from both regions is used to calculate Compton scattering, Compton drag and photon–photon opacity effects, with exact treatment of anisotropy and the Klein–Nishina regime. Radiative effects on plasma are taken into account, including the dependence of pressure on electron radiative losses and adiabatic heating of the flow decelerating under Compton drag. The results are applied to the 2006 July flare in the BL Lac object PKS 2155−304, with the aim of matching TeV flux measurements by the High Energy Stereoscopic System (HESS) with models that satisfy the variability constraints, while keeping X-ray emission below simultaneous Chandra observations. We find that models of isolated minijets with a significant guide field overproduce X-ray emission, and that we must take into account the radiative interaction of oppositely oriented minijets in order to achieve a high enough dominance by Comptonized TeV radiation. We argue that such interactions are likely to occur in a jet where there is substantial internal reconnection, producing a large number of misaligned minijets. Finally, we show that large jet magnetizations are indeed required to satisfy all observational constraints and that the effective Lorentz factor of the minijet plasma has to be larger than 50, in agreement with earlier one-zone estimates.