Annihilation luminosity expected in the simulation by Schulreich et al. (2023) from only the charge exchange annihilation channel. Shown is the cell-averaged total luminosity for a slice through y = 0 pc. Clearly, boundary of the supershell shows the highest luminosity, together with the clouds inside the bubble. We again use the condition that the flow velocity must be larger than 1 km s⁻¹ to distinguish the bubble from the background medium (see also Fig. 2).