Theoretical spectral energy distributions of the γ-rays resulting from pion decay inside a turbulent superbubble for different values of the acceleration efficiency parameter ξ (according to Tolksdorf et al. 2019). The efficient case (ξ = 0.1) is in blue, the intermediate one (ξ = 1) in green and the inefficient case (ξ = 10) in orange. All distributions are normalised to one at the pion mass. For a better readability, the SED for ξ = 1 and ξ = 10 are divided by a factor of two and four, respectively.