Line/FIR ratios of the z = 6.08 quasar J2100–Q and its companion J2100–SB compared to the local LIRG compilation by Díaz-Santos et al. (2017). The data points are color-coded by FIR luminosity, circles (stars) mark sources with an AGN contribution of >50% (<50%) in the MIR (Díaz-Santos et al. 2017). Left panel: [O III]88/FIR luminosity ratio as a function of the continuum flux density ratio (S88 μm/S158 μm). This ratio is a proxy for the temperature as shown on the top x-axis, assuming a modified blackbody with β = 1.6 for the dust emissivity. Middle and right panels: same x-axis as in the left panel but now showing the [C II]/FIR luminosity ratio and the [O III]/[C II] ratio, respectively.