Observed FWHM of the [C II] 158 μm line as function of the [C II] luminosity from ALPINE and other data from the literature (the compilation of z >  6 sources from Matthee et al. 2019) and available measurements for galaxies in the Zanella et al. (2018) compilation (z ∼ 0 − 6). The violet dashed line is a Tully-Fisher-like relation derived for high-z galaxies by Kohandel et al. (2019). The green solid line shows our best fit to the data.