Axial cuts of different quantities for simulation S2 at t ≃ 3.1 × 10⁵   s, during the initial phase, before the shock completely crosses the obstacle. The top left panel shows L_j,g1 − L_j,int,g1 for the jet material (solid line) normalized to its injection value 3.5 × 10⁴²   erg/s, and the internal energy luminosity L_j,int,g1 normalized to its maximum value, 5.6 × 10⁴⁰   erg/s (dashed line); the red solid line stands for the internal energy luminosity in the jet material, and the blue dotted line for the internal energy luminosity in the obstacle material. The top right panel shows the mass flux, normalized to its maximum value (4 × 10²²   g/s). The bottom left and right panels show the mean velocity and density in the obstacle gas.