Top: Modeled photon flux in two polarization modes. The figure emphasizes the formation of a strong red wing due to redistribution near cyclotron resonance. Simulations were performed for a homogeneous slab of self-emitting magnetized plasma with τ_T = 1000, n_e = 10²² cm⁻³, kT_e = 5 keV, and E_cyc = 20 keV. The spectra for each polarization mode are integrated over angles. Photon polarization modes, mode 1 (F₁) and mode 2 (F₂), include vacuum effects and plasma polarization (corresponding to the continuous behavior of the refractive indices, see Sokolova-Lapa et al. 2023, for more details). Assuming a gravitational redshift of (1 + z) = 1.24, the cyclotron line in the final spectrum appears at 15 keV. The spectra are shown on the redshifted energy grid. A fit to the power-law spectrum with a high-energy cutoff (cutoffpl), using a photon index of Γ = 0.47, a cutoff energy of E_fold = 6.6 keV, and a normalization of N = 2.4 × 10³², is shown in energy flux space to illustrate the generally assumed continuum behavior. Bottom: Ratio between the modeled photon flux and cutoffpl.