In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 10⁹ M _⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.

2017 年，事件视界望远镜 (EHT) 合作成功地捕捉到了 M87 星系中心的第一张直接图像。不对称环的形态和大小与质量为∼6.5 10 ⁹ M _⊙的弱吸积超大质量黑洞的理论预期一致. EHTC 还与太空和地面上的几个国际设施合作，安排了一次广泛的、准同步的多波长活动。这封信介绍了这次活动的结果和分析，以及作为遗留数据存储库的多波长数据。我们捕获了处于历史低位状态的 M87，并且核心通量在高能量下高于 HST-1，从而可以将核心通量约束与空间更精确的超长基线干涉测量数据结合起来。我们提供了迄今为止最完整的活动核同步多波长光谱，并讨论了将不同空间尺度的数据组合成一个宽带光谱的复杂性和注意事项。我们应用两个启发式的、各向同性的轻子单区模型来深入了解基本的源属性，但得出结论，结构化喷流对于解释 M87 的频谱是必要的。我们可以排除同时γ射线发射是通过在产生 EHT 毫米波段发射的同一区域的逆康普顿发射产生的，并进一步得出结论，如果存在强粒子，γ射线只能在内部射流（HST-1 内部）中产生。 - 主导的地区。还不能排除来自加速质子和次级的直接同步加速器发射。