I am quite impressed with the recently published image of M87* black hole. It appears that this image achieves spatial resolution well above and beyond what was available until today. But how high this resolution is, exactly?
The article "First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole" states that Event Horizon Telescope has theoretical diffraction-limit resolution of ~25 μas.
Another wiki article states that M87* has Swartzschild radius of 5.9×10-4 parsecs. Combined with the distance of 16.4 million parsecs, this gives me angular size of 14.8 microarceconds.
Even with the shadow of the black hole being 2.5 bigger that its radius, the resolution of a widely distributed picture seems to be much higher than 25 microarcseconds stated above. Is the image actually blown up well beyond its original resolution (i.e. becoming more a less an "artistic impression"), or Event Horizon Telescope is actually capable of higher resolutions (10 microarcseconds or less)?