Best-fit values of the spectral index γ (left panel) and the total energy carried by positrons fW₀ (right panel) for each point of the plane (age, distance) with the benchmark propagation model MED. The grey lines display the iso-contours for given values of γ (left) and fW0 (right). The black dashed lines represent the iso-contours of the critical p-values. The five selected pulsars with their associated uncertainty on their distance are indicated by the black stars.