In 2017, the first image of the center of the M 87 galaxy was captured by the Event Horizon Telescope (EHT). It revealed a ring morphology and a size consistent with with theoretical expectations for the light pattern around a weakly accreting supermassive black hole of mass of ~6.5 billion solar masses. In parallel to the EHT measurements, an extensive multi-wavelength campaign with ground- and space-based facilities from radio all the way up to the TeV range was organized.
In this presentation we will give an overview of the results from this campaign. M87 was found to be in a historical low state, both for its core and the nearest knot HST-1. In the high-energy range, at X-ray energies, the emission from the core dominates over HST-1.
We present the most complete simultaneous, multi-wavelength spectrum of the active nucleus to date, as well as discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum.