The Event Horizon Telescope probed the region near the supermassive black hole of the active Perseus A galaxy and estimated the parameters of its magnetic field. Observational data suggest that magnetic fields play an important role in accretion currents and jet formation. This paper was published in the journal Astronomy & Astrophysics. Relativistic plasma (jet) jets are observed in galaxies with active nuclei containing supermassive black holes surrounded by accretion disks, and have a major impact on galaxy evolution. There are two main theories for the formation of such flows associated with rotating black holes. According to the first, the rotational energy of a black hole can be extracted by a large-scale toroidal magnetic field (Blandford-Payne mechanism) or poloidal magnetic field (Blandford-Znajek mechanism) that penetrates the disk. According to the second (Penrose mechanism), a particle that flies into the ergosphere of a black hole splits into two parts, one of which is thrown away, consuming a lot of energy. It is also possible that material flows magnetohydrodynamically from within the accretion disk. Despite the large amount of observational data on such structures, scientists still have many questions, including how they formed. A team of astronomers led by Georgios Filippos Parashos of the Max Planck Institute for Radio Astronomy has published observations about the environment of a supermassive black hole in the nearby active galaxy Perseus A (or 3C 84). This phenomenon was observed with a global radio interferometer with a very long baseline EHT (Event Horizon Telescope) at a frequency of 228 gigahertz. The observations were carried out in 2017 and covered an area with a Schwarzschild radius of 500 near the 800 million solar mass black hole. The scientists also compared the EHT data to other radio telescope observations of Perseus A. Scientists discovered three luminescent components, one of which is the core. Highly ordered magnetic fields have been discovered around black holes, and the black holes themselves rotate at high speeds. The uniformly distributed magnetic field strength is estimated to be 5.2 Gauss. The model that best fits the observational data is that of a magnetically dominated thick disk (magnetically stopped disk) in which advection (responsible for cooling the disk) is dominant. There, magnetic fields can strongly influence accretion and slow down the jet. To the Blandford Znajek Organization.