Magnetic field configuration on a large scale related to the observed region of the diffuse emission. We show the long-range magnetic connections starting from the vicinity of the diffuse region calculated from a PFSS extrapolation. The background image is a line-of-sight magnetogram from HMI, in which the red box outlines the same area as the red box in Fig. 1a. The diffuse region is located close to the center of the red box. See Sect. 3.5.