Emission pattern of the specific intensity in polar (left) and Cartesian (right) coordinates for the NS atmosphere models presented in Fig. 4. The dashed curves show the patterns for non-heated atmosphere model, and the solid curves are for a power-law distribution of return current particles. Top, middle and bottom panels correspond to δ = 1, 2 and 3, respectively. The black, blue, green, orange, and red colours correspond to intensities at 0.1, 0.3, 1, 3, and 10 keV, respectively.