2025RAA....25g5003L

This paper presents a statistical study of the division of the [C II] 158 μm line into ionized and neutral components, using a new carbon-to-nitrogen abundance ratio, log(C/N) = 0.75, for a sample of 108 local galaxies. We investigate the correlation between the ionized-to-total [C II] ratio ([C II]_ionized/[C II]_total) and the far-infrared color f60/f100, finding a moderate negative correlation. Additionally, we explore the dependence of [C II]_ionized/[C II]_total on various physical properties. We find that [C II]_ionized/[C II]_total exhibits a weak negative correlation with the offset from the main sequence and a moderate negative correlation with the [O III]88 μm/ [N II] 122 μm. Furthermore, no significant correlation with molecular gas mass is found. It shows a positive correlation with metallicity. Our results suggest that [C II]_ionized/[C II]_total is influenced by the ionization parameter, star formation efficiency and metallicity.