Pair-regulated Klein–Nishina relativistic magnetic reconnection with applications to blazars and accreting black holes
Pair-regulated Klein–Nishina relativistic magnetic reconnection with applications to blazars and accreting black holes
复制标题
配对调节克莱因·仁科相对论磁重联及其在耀变体和吸积黑洞中的应用
DOI：
10.1093/mnras/stab2745
复制
发表时间：
2021
影响因子：
4.8
通讯作者：
Begelman, M C
中科院分区：
文献类型：
--
作者：
Mehlhaff, J M;Werner, G R;Uzdensky, D A;Begelman, M C
相对论磁场重联是一种强大的媒介，通过它可以在天体物理学中利用磁能，激发粒子，然后产生观测到的辐射。在一些系统中，最高能量的光子来自对由外部源供应的环境辐射浴进行康普顿化的粒子。如果发射粒子的能量足够高，这种逆康普顿（IC）散射就进入克莱因-西名区域，这与低能汤姆逊IC极限有两个显著的不同。首先，辐射损失变得固有地离散，粒子将其能量的一个阶单位分数传递给单个光子。其次，康普顿化光子可以与环境辐射配对产生，为磁场重联的辐射反馈开辟了另一条通道。我们分析研究外部照明的高磁化重连系统，这两个影响是重要的。我们确定了一个普遍的（初始磁化独立）准稳态，其中从重连层发射的伽马射线被吸收在上游区域，由此产生的热对占主导地位的流入等离子体的能量密度。然而，一个真正的对级联是不太可能的，和创建对的数密度仍然subdominant到原始等离子体的一个宽的参数范围。未来的粒子模拟研究可能会测试各个方面。对调节克莱因-西那重联可以解释陡峭的光谱（静态和耀斑）从平谱射电类星体和黑洞吸积盘冠。
Relativistic magnetic reconnection is a powerful agent through which magnetic energy can be tapped in astrophysics, energizing particles that then produce observed radiation. In some systems, the highest energy photons come from particles Comptonizing an ambient radiation bath supplied by an external source. If the emitting particle energies are high enough, this inverse Compton (IC) scattering enters the Klein–Nishina regime, which differs from the low-energy Thomson IC limit in two significant ways. First, radiative losses become inherently discrete, with particles delivering an order-unity fraction of their energies to single photons. Secondly, Comptonized photons may pair produce with the ambient radiation, opening up another channel for radiative feedback on magnetic reconnection. We analytically study externally illuminated highly magnetized reconnecting systems for which both of these effects are important. We identify a universal (initial magnetization-independent) quasi-steady state in which gamma-rays emitted from the reconnection layer are absorbed in the upstream region, and the resulting hot pairs dominate the energy density of the inflow plasma. However, a true pair cascade is unlikely, and the number density of created pairs remains subdominant to that of the original plasma for a wide parameter range. Future particle-in-cell simulation studies may test various aspects. Pair-regulated Klein–Nishina reconnection may explain steep spectra (quiescent and flaring) from flat-spectrum radio quasars and black hole accretion disc coronae.