Magnetic amplitude in log    μG with magnetic vectors overplotted (upper panels) and the pitch angle θ_p in degrees (bottom panels) for the galaxy without star formation at t ≃ 3 Gyr (left panels), for the galaxy with star formation and without feedback at t = 4 Gyr (middle panels), and for the galaxy with star formation and supernova feedback at t = 3 Gyr (right panels) in the upper part of the equatorial plan. The initial magnetic field is B_IGM = 10^-5 μG. The picture size is 40 kpc.