Temporal evolution of the monochromatic UV luminosity L₁₅₀₀ (left) and the UV star formation rate conversion factor κ_UV (right panel, for SFR = const) predicted for models with a Salpeter IMF slope (α₂ = −2.35) and a flatter IMF (α₂ = −2.). L₁₅₀₀ is normalized to 10⁶ M_⊙ for bursts and to 1 M_⊙ yr⁻¹ for SFR = const. The models with a Salpeter slope are shown using the same colors as in previous figures. Models with the flat IMF, including also nebular emission), are shown by yellow and green lines. VMS-only models and PopIII models with a top-heavy IMF are shown by dotted lines. All models shown here include nebular continuum emission. Dash-dotted horizontal lines in the right panel show the value of the canonical SFR(UV) conversion factor from Madau & Dickinson (2014) for a Salpeter and a Kroupa IMF.