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Abstract The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation 1, 2. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1. 3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole 3. Here we report images of M87 obtained in 2018, at a wavelength of 3. 5 mm, showing that the compact radio core is spatially resolved. High-resolution imaging shows a ring-like structure of 8. 4-₁. ₁^+0. 5 8. 4 − 1. 1 + 0. 5 Schwarzschild radii in diameter, approximately 50% larger than that seen at 1. 3 mm. The outer edge at 3. 5 mm is also larger than that at 1. 3 mm. This larger and thicker ring indicates a substantial contribution from the accretion flow with absorption effects, in addition to the gravitationally lensed ring-like emission. The images show that the edge-brightened jet connects to the accretion flow of the black hole. Close to the black hole, the emission profile of the jet-launching region is wider than the expected profile of a black-hole-driven jet, suggesting the possible presence of a wind associated with the accretion flow.
Lu et al. (2023) studied this question.