Evolution of the QPE spectral energy distribution with the relative accretion rate. Top panel: Blackbody spectra of ejected plasmoids (black lines) for different relative accretion rates (ṁ = 1−0.01), which influence the post-shock radiation temperature. The blue shaded rectangle depicts the spectral range between 0.2 and 2 keV. For comparison, we also depict corresponding AGN spectra (standard accretion disks, orange colors) and their sum with QPE spectra (green lines). Bottom panel: Dependence of the ratio between the X-ray (0.2-2 keV) luminosity and the bolometric luminosity, L_x/L_bol, as a function of the relative accretion rate. The curve is color-coded using the post-shock radiation temperature.