发表机构
Radboud University（拉德堡德大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文基于EHT 2026年多频观测计划，通过EBHLIGHT和IPOLE模拟预测M87*谱指数图，研究电子分布模型和自旋对时间变异性的影响，并与观测对比约束参数。
AI 中文摘要
从2026年3月开始，事件视界望远镜（EHT）开展了一项为期两个月的观测活动，旨在获取室女座A星系中心黑洞M87*的首个时间分辨图像序列。该活动的主要科学目标是约束黑洞自旋，并研究视界尺度喷流发射区域内磁场和等离子体性质的时间变化。在本工作中，我们提出了对这些观测预期的谱指数图的 theoretical 预测。我们的预测基于使用EBHLIGHT代码进行的磁 arrested 盘模拟，并使用IPOLE广义相对论光线追踪代码进行后处理。我们研究了在多种电子分布模型和五个不同黑洞自旋值下谱指数的时间演化。分析涵盖了EHT当前存在的频段以及为未来EHT阵列扩展提出的邻近频率。除了将先前研究扩展到更广泛的观测频率范围外，我们的工作还系统地研究了预测谱指数图的时间变异性。在纯热电子模型中，谱指数图的时间变异性紧密追踪事件视界附近磁场强度和电子温度的变化。相比之下，包含非热电子群的模型表现出明显较弱的谱指数变异性，这是由于具有固定谱斜率的幂律分量的贡献。我们的数值结果与理论预期一致。最后，与最近测得的M87*积分谱指数的比较使我们能够对模型参数施加初步约束。
英文摘要
Beginning in March 2026, the Event Horizon Telescope (EHT) conducted a two-month observing campaign aimed at obtaining the first time-resolved sequence of images of the black hole M87* at the center of the Virgo A galaxy. The primary scientific objectives of this campaign are to constrain the black hole spin and to investigate the temporal variability of the magnetic field and plasma properties within the horizon-scale jet-launching region. In this work, we present theoretical predictions for the spectral index maps expected from these observations. Our predictions are based on Magnetically Arrested Disk simulations performed with the EBHLIGHT code and post-processed using the IPOLE general relativistic ray-tracing code. We investigate the temporal evolution of the spectral index for a range of electron distribution models and five different black hole spin values. The analysis includes both frequency bands currently present within the EHT and neighboring frequencies proposed for future extensions of the EHT array. In addition to extending previous studies to a broader range of observing frequencies, our work systematically investigates the time variability of the predicted spectral index maps. In purely thermal electron models, the temporal variability of the spectral index maps closely traces variations in the magnetic field strength and electron temperature in the immediate vicinity of the event horizon. By contrast, models incorporating a non-thermal electron population exhibit substantially weaker spectral index variability, owing to the contribution of a power-law component with a fixed spectral slope. Our numerical results are consistent with theoretical expectations. Finally, a comparison with the recently measured integrated spectral index of the M87* enables us to place preliminary constraints on the model parameters.
Comments20 pages, 23 figures. Submitted to Monthly Notices of the Royal Astronomical Society
