The fundamental metallicity relation from z ∼ 0 to z ∼ 0.7: Selection or Evolution?

Galaxy metallicity, as a result of the integrated star formation history and evolution of the interstellar medium, is an important property describing galaxy evolution. Its relation with galaxy stellar mass and star formation rate (SFR), known as the fundamental metallicity relation (FMR), has been widely studied, especially in the local Universe. However, when it comes to the evolution of the FMR, most of the studies are based on very different samples, with different data selections at different redshift ranges. We check how different selection biases affect the FMR projections. This will allow us to separate the real physical evolution from the false evolution introduced by these biases. We find significant differences between FMR projections occurring when different ways of data selection, simulating the selection of higher redshift samples, are applied to the SDSS data at z ∼ 0. Then, we compare the results with the findings from the VIPERS sample at z ∼ 0.7. We conclude that both FMR and its projections at z ∼ 0.7 and z ∼ 0 are in good agreement. When the data selection effects are carefully applied the differences between samples are reduced, especially at high stellar mass, but these biases are not able to reproduce the flattening at low stellar mass showed by the sample at z ∼ 0.7.