Flux tubes in the 3D GRMHD simulations. They are visualized with meridial (panels a, b, c) and equatorial (d, e, f) slices and correspond to low-density (ρ), high-magnetization (σ in Fig. C.1) regions that come about after a magnetically driven flux eruption starting from the central BH. The chosen slices correspond to promising time lag windows, as listed in Table D.1. Most jet-related emission is expected from low-density (ρ ∼ 10⁻²) transition region known as the jet sheath (see panels a, b, c).