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tokens: BH (), but in this case the BH shadow at millimeter wavelengths is also illuminated by the counter-jet, which is geometrically more extended compared to our GRMHD numerical models. Broderick Loeb (2009) did not restrict the orientation of appropriate baselines to E-W direction in their analysis because their counter-jet emission is more uniform and extended compared to ours. At 7 mm, the size of the jet emission in their model is sensitive to the jet collimation parameter, . It is quite possible that our model will also be sensitive to the exact value of the BH spin or the disk size that may control the jet collimation. We leave this issue for a future study. 4.6. Matter content of the jet funnel Unlike those by Broderick Loeb (2009) and Dexter et al. (2012) , our model does not make any assumption about the jet matter content. At the jet wall (sheath), the plasma is baryonic, and it is constantly supplied from the accretion disk. Inside of the jet funnel, electron-positron pairs are produced in collisions. We calculate the pair production rate directly from the RT model following Mościbrodzka et al. (2011) . In model RH100, the pair production rate near the SMBH horizon is (based on Eq. (26) in Mościbrodzka et al. 2011 , assuming that the luminosity of the source around the electron rest-mass energies is ). This gives an estimate for the pair plasma density near the event horizon . Using Eq. 45 in Mościbrodzka et al. (2011) , we can calculate the Goldreich–Julian density , i.e. the pair density required to enforce the ideal MHD condition () in the rest frame of the plasma ( Goldreich Julian 1969 ). We find that in model RH100; i.e., the pairs cannot be produced in cascades and multiply themselves. In summary, the pair density in the jet funnel (spine) remains low. 4.7. Emission from the jet sheath in radio Finally, we briefly discuss the effect of the jet vertical stratification (jet spine and sheath) on the observational properties of jets in general. A recent work by Boccardi et al. (2015) reports the detection of the edge-brightened jet in Cyg A. The jet in Cyg A jet is not resolved by radio observations as well as is the M 87 jet. Therefore we should keep in mind that their scales are different and their inclination angles are also probably different. The authors report that the counter-jet is narrower than the approaching jet. To clarify what our models predict we plot our 43 GHz images of the M 87 jet at various inclination angles in Fig. 11 . Here we do not notice any evident difference in the opening angle of the jet and counter-jet owing to the geometrical effects of light propagation. However, we find that the jet edge-brightening depends on inclination, and it becomes more notable for . In the images presented in Sect. 3 , the signal-to-noise ratio is greatly improved thanks to the time-averaging of many frames. However, we notice that single images of the jet at longer wavelengths exhibit some numerical artifacts. These are most