发表机构
University of Rochester; Laboratory for Laser Energetics, University of Rochester（罗切斯特大学; 罗切斯特大学激光能源实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过广义平均场吸积盘理论及数值模拟，验证了磁浮力供应的冕模型，其预测的X射线光子指数与塞弗特星系观测值一致，支持该范式。
AI 中文摘要
对塞弗特星系等活动星系核的标准辐射谱建模通常需要手动调节光学厚盘、光学薄冕、尘埃环和出流的相对贡献以匹配观测。量化这种相对分配的物理机制尚未被精确理解。在此，我们通过检验一个概念范式的含义来推进这一理解：冕仅由下方磁场供应，这些磁场的尺度足够大，能在其浮升时间内逃脱湍流撕裂。我们使用包含局域径向角动量输运和向冕的角动量输运的广义平均场吸积盘理论。然后，我们利用先前磁化湍流吸积盘能量谱的数值模拟，将逃逸的盘磁能比例与冕对总光度之比联系起来。在不显式计算详细粒子加速和辐射过程的情况下，我们假设盘辐射谱为热谱，冕辐射谱为幂律。我们随后证明，上述冕形成范式将允许的X射线幂律指数限制在一个狭窄范围内，该范围与观测一致。对于此处研究的三个活动星系核，预测的平均光子指数为$\overline{\Gamma}=1.76$，与观测平均值$\overline{\Gamma}_{\rm obs}=1.73$一致，增强了对该范式的信心。
英文摘要
Standard radiation spectra modeling of active galactic nuclei like Seyfert galaxies typically involves tuning the relative contributions from an optically thick disc, optically thin corona, dust torus, and outflow by hand to match observations. The physics that quantifies this relative partitioning is not precisely understood. Here we make progress toward improving this understanding by testing the implications of a conceptual paradigm that the corona is supplied from below only by magnetic fields whose scales are large enough to escape turbulent shredding on their buoyant rise time. We use a generalized mean field accretion disc theory that includes both local radial angular momentum transport and angular momentum transport into a corona. We then use previous numerical simulations of magnetized turbulent accretion disc energy spectra to connect the fraction of disc magnetic energy that would escape to the fraction of coronal to total luminosity. Without explicitly calculating detailed particle acceleration and radiative processes, we assume that the disc radiation spectrum is thermal and the coronal radiation spectrum is a power law. We then show that the aforementioned paradigm for corona formation constrains the allowed x-ray power law index to a narrow range which agrees with observations. For the three AGNs studied here the predicted mean photon index is $\overlineΓ=1.76$, consistent with the mean observed value of $\overlineΓ_{\rm obs}=1.73$, bolstering confidence in the paradigm.
Comments10 pages, 2 tables, 6 figures, submitted to Publications of the Astronomical Society of Australia (PASA)
