Velocity gradient maps of the red- (top) and blueshifted (bottom) part of the gas bridge. In each row, the velocity (left), velocity gradient (center), and velocity gradient PA (right) are shown in color. The black contours are the 1.4 mm continuum with levels at 5, 10, 20, 40, 80, and 160×σ_cont (σ_cont=0.94mJybeam⁻¹). The purple arrows in the left panels indicate the direction and strength of the velocity gradient, where the arrow tip points from low to high velocities. The length of the purple arrow in the bottom left corner marks a velocity gradient of 100 km s⁻¹pc⁻¹. In the top left panel, the synthesized beam of the NOEMA line and continuum data are shown in the bottom left and right corner, respectively. A scale bar is shown in the top left corner, and bipolar outflow orientations are highlighted by red and blue arrows (Sect. 3.2).