Balancing turbulent heating with radiative cooling in blazars
Balancing turbulent heating with radiative cooling in blazars
复制标题
平衡耀变体中的湍流加热与辐射冷却
DOI：
10.1093/mnras/stac1282
复制
发表时间：
2022
影响因子：
4.8
通讯作者：
Giannios, Dimitrios
中科院分区：
文献类型：
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作者：
Davis, Zachary;Rueda-Becerril, Jesús M.;Giannios, Dimitrios
最近，粒子在细胞（PIC）模拟表明，在无碰撞等离子体中的相对论湍流可以导致一个平衡的粒子分布函数，其中湍流加热平衡的电子辐射冷却。强磁化等离子体的特征是具有更高的能量峰值和更宽的粒子分布。在相对论运动的天体物理喷流中，人们认为，喷流是由坡印廷通量主导的，由此产生的磁不稳定性可能会在喷流内部产生湍流环境，即相对论湍流状态。在本文中，我们扩展以前的PIC模拟结果，等离子体磁化强度较大的值，通过线性外推的扩散和平流系数相关的湍流等离子体考虑。我们使用这些结果来建立一个单区湍流射流模型，该模型是基于blazar发射区的全局参数，并一致地计算粒子分布和由此产生的发射光谱。然后，我们测试我们的模型进行比较，其预测与宽带静态发射光谱的十几个耀变体。我们的结果与低同步辐射峰值（LSP）源的观测结果吻合较好，发现LSP为中等强度的坡印廷磁通，主导磁化强度为1 <$σ <$5，体洛伦兹因子为10-30，湍流区位于边缘，或刚好超出宽线区（BLR）。湍流被发现是在一个区域驱动的射流横截面。
Recently, particle-in-cell (PIC) simulations have shown that relativistic turbulence in collisionless plasmas can result in an equilibrium particle distribution function where turbulent heating is balanced by radiative cooling of electrons. Strongly magnetized plasmas are characterized by higher energy peaks and broader particle distributions. In relativistically moving astrophysical jets, it is believed that the flow is launched Poynting flux dominated and that the resulting magnetic instabilities may create a turbulent environment inside the jet, i.e. the regime of relativistic turbulence. In this paper, we extend previous PIC simulation results to larger values of plasma magnetization by linearly extrapolating the diffusion and advection coefficients relevant for the turbulent plasmas under consideration. We use these results to build a single-zone turbulent jet model that is based on the global parameters of the blazar emission region, and consistently calculate the particle distribution and the resulting emission spectra. We then test our model by comparing its predictions with the broad-band quiescent emission spectra of a dozen blazars. Our results show good agreement with observations of low synchrotron peaked (LSP) sources and find that LSPs are moderately Poynting flux dominated with magnetization 1 ≲ σ ≲ 5, have bulk Lorentz factor Γj∼ 10–30, and that the turbulent region is located at the edge, or just beyond the broad-line region (BLR). The turbulence is found to be driven at an area comparable to the jet cross-section.