Spiral galaxy model described in Sect. 6 and Table 2 observed at a wavelength of 1 μm. Rows from top to bottom: face-on, inclined (53°), and edge-on surface brightness (color scale) overlaid with linear polarization degree and orientation (line segments); linear polarization degree of the edge-on view, averaged over the vertical axis. Columns from left to right: the reference model; the same model observed from a different azimuth angle (rotated clockwise by 120°); a model without the spiral arm perturbations in the stellar disks, with the rotated orientation.