  The formation of jets in black hole accretion systems is a long-standing
problem. It has been proposed that a jet can be formed by extracting the
rotation energy of the black hole ("BZ-jet") or the accretion flow
("disk-jet"). While both models can produce collimated relativistic outflows,
neither has successfully explained the observed jet morphology. By employing
general relativistic magnetohydrodynamic simulations, and considering
nonthermal electrons accelerated by magnetic reconnection that is likely driven
by magnetic eruption in the underlying accretion flow, we obtain images by
radiative transfer calculations and compared them to millimeter observations of
the jet in M87. We find that the BZ-jet originating from a magnetically
arrested disk around a high-spin black hole can well reproduce the jet
morphology, including its width and limb-brightening feature.
