Correlation between bolometric luminosity and radio continuum luminosity at centimetre wavelengths (dashed line and shaded area). Squares represent very low luminosity (L_bol < 1 L_⊙), circles low luminosity (1 ≤ L_bol ≤ 1000 L_⊙), and triangles high luminosity sources (L_bol > 1000 L_⊙). The dot-dashed line represents the expected radio luminosity of an optically thin region photo-ionised by Lyman continuum. The red circle corresponds to a L_bol ∼ 600 L_⊙ assuming all radio flux comes from shocked-excited jet emission, whereas the red triangle corresponds to a L_bol ∼ 1300 L_⊙ assuming all radio flux comes from an optically thin H II region. Both have been calculated using S_νd² = 0.55 mJy kpc², with ν = 8.19 GHz. The figure is adapted from Anglada et al. (2018).