Left panel: Hα channel map between 150 <v< 500 km s^-1, showing the redshifted expanding bubble to the NE. Central panel: channel map between − 500 <v< − 180 km s^-1 shows the corresponding blueshifted bubble to the SW. The yellow circle indicates the spaxels from which the spectrum of the [NII] and Hα region shown in the right panel is extracted. The double-peaked profile of Hα and [NII] is evident with a shift between the two peaks of 310 km s^-1. The shaded cyan region indicates the velocity range used for the channel map shown in the central panel.