标题： 耀变星系中的重联驱动小喷流的辐射特性 显示英文标题

标题： Radiative Properties of Reconnection-Powered Minijets in Blazars

摘要： 我们构建了一个关于喷流中磁重联驱动的小尺度喷流发射的数值模型，用以解释耀变体的超快光变。 该模型的几何结构由两个楔形区域组成，区域内为相对论性流动气体，两区域之间由一个驻定激波分隔。 动力学基于Lyubarsky（2005）提出的具有引导磁场的相对论磁重联解。 每个区域内的电子分布被选择以匹配局部等离子体的压力和密度。 使用两个区域的同步辐射来计算康普顿散射、康普顿拖拽以及光子-光子对消效应，并精确处理各向异性及Klein-Nishina区域。 考虑了辐射对等离子体的影响，包括压力依赖于电子辐射损失以及减速过程中受康普顿拖拽影响的流体绝热加热。 将结果应用于BL Lac天体PKS 2155-304的2006年7月爆发，旨在通过满足变率约束条件的模型匹配H.E.S.S.的TeV流量测量值，同时使X射线发射低于同时期Chandra观测值。 我们发现孤立小尺度喷流模型在显著引导场情况下过度产生X射线发射，必须考虑反向小尺度喷流之间的辐射相互作用才能达到足够的康普顿化TeV辐射主导地位。 我们认为这种相互作用很可能发生在内部重联显著的喷流中，产生大量方向不一致的小尺度喷流。 最后，我们表明确实需要大磁化度的喷流来满足所有观测限制，且小尺度喷流等离子体的有效洛伦兹因子必须大于50，这与早期的一区估算结果一致。 显示英文摘要

摘要： 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 (2005). Electron distributions in each region are chosen to the 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 July 2006 flare in the BL Lac object PKS 2155-304, with the aim of matching TeV flux measurements by H.E.S.S. 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.