Polarization map of the thermal emission of our reference model with a total mass of M_gas = 40 M_⊙ inside of R = 1.5 × 10⁴ AU (λ = 450 μm). The image shows the innermost 80′′ × 80′′ (corresponding to 8000 AU × 8000 AU). The orientation of the white lines show the polarization angle and their length show the degree of polarization. The white dashed contour line shows the line-of-sight optical depth τ_LOS = 1. The orientation of the magnetic field lines is parallel to the y-axis.