Dependence of the spatial extent of [C II] line emission on the SFR_IR surface density. (Left) [C II] line radius as a function of the SFR_IR surface density. The solid blue and purple lines show a best-fit linear regression for single and single+pair sources, respectively. The shaded region shows a 95% confidence level of the fit for single galaxies. The p values of a Spearman’s rank correlation test for both single and single+pair parent samples are shown in the lower-left corner. We also highlight CRISTAL-02 (multiple-UV), a galaxy which shows an evidence of broad [C II] wing component in multiple spatially resolved elements of the galaxy (Davies et al. in prep). (Right) Same as the left panel, but taking the [C II]-to-UV size ratio as the vertical axis. Given the p values, we cannot rule out the null hypothesis that there is no correlation between these parameters.