On the universality of luminosity–metallicity and mass–metallicity relations for compact star-forming galaxies at redshifts 0 < z < 3

We study relations between global characteristics of low-redshift (0 < z < 1) compact star-forming galaxies, including absolute optical magnitudes, H β emission-line luminosities (or equivalently star formation rates), stellar masses, and oxygen abundances. The sample consists of 5182 galaxies with high-excitation H ii regions selected from the SDSS DR7 and SDSS/BOSS DR10 surveys adopting a criterion [O iii] λ4959/H β ≥ 1. These data were combined with the corresponding data for high-redshift (2 ≲ z ≲ 3) star-forming galaxies. We find that in all diagrams low-z and high-z star-forming galaxies are closely related indicating a very weak dependence of metallicity on stellar mass, redshift, and star formation rate. This finding argues in favour of the universal character of the global relations for compact star-forming galaxies with high-excitation H ii regions over redshifts 0 < z < 3.