Stellar (left) and X-ray (right) incident SEDs of Cloudy models for a solar metallicity and bolometric luminosity of 10⁹ L_⊙. Q_E shows the number of photons produced above a given energy E_ν. The vertical dashed lines represent the ionization potentials of H⁺ (13.6 eV), O²⁺ (35.1 eV), O³⁺ (54.9 eV) and Ne⁴⁺ (97.1 eV). Left-hand side: the dashed lines represent BPASS models with binary stars while the solid lines of the same color correspond to BPASS models without binary stars for a single stellar population of the same age. The change in the spectra due to the inclusion of binary stars is represented by the shaded area in between both lines. The insert shows a zoom around the Lyman edge at 912 Å where the additional contribution to ionizing photons is visible for ages above 3 Myr and increases with the age of the burst. Right-hand side: the colors represent different inner temperature of the multicolor blackbody and the different linestyles to different percentage of stellar luminosity: 0.001%, 0.01% and 0.1%.