Research Gallery

Superluminal motions are widely detected in AGN jets by utilizing the VLBI technique, implying that the flow is highly relativistic (apparent speeds are exceeding the speed of light ~ 10 - 30 c). We however do not understand how/where they are originated. We conduct a high resolution GRMHD simulations and reveal the formation of superluminal blobs near the funnel edge of the black hole driven jets. A filled color contour shows the Lorentz factor and FWHM/2 of mm VLBI radio core sizes in M87 are also displayed. Beyond R ~ 10 r_g (outside the light cylinder), the flow becomes super-Alfvenic, suggesting the toroidal field component becomes dominant. In this simulation, an axisymmetric mode (m=0) of the plasma instability (sausage type) is presumably growing due to the dynamical confinement of the funnel by the external coronal wind. Enhanced peaks of the Lorentz factor can be a seed of superluminal blobs, which may cause a local energization of the synchrotron particle. We can test our model by monitoring the variation of the flux density as well as the size of VLBI cores including the sub-mm VLBI cores (EHT).