Physical properties of galaxies and their evolution in the VIMOS VLT Deep Survey: II. Extending the mass-metallicity relation to the range z ≈ 0.89'1.

Aims. We present a continuation of our study about the relation between stellar mass and gas-phase metallicity in the VIMOS VLT Deep Survey (VVDS). In this work we extend the determination of metallicities up to redshift ≈1.24 for a sample of 42 star-forming galaxies with a mean redshift value of 0.99.Methods. For a selected sample of emission-line galaxies, we use both diagnostic diagrams and empirical calibrations based on [Oii] emission lines along with the empirical relation between the intensities of the [Oiii] and [Neiii] emission lines and the theoretical ratios between Balmer recombination emission lines to identify star-forming galaxies and to derive their metallicities. We derive stellar masses by fitting the whole spectral energy distribution with a set of stellar population synthesis models.Results. These new methods allow us to extend the mass-metallicity relation to higher redshift. We show that the metallicity determinations are consistent with more established strong-line methods. Taken together this allows us to study the evolution of the mass-metallicity relation up to ≈ ≈ 1.24 with good control of systematic uncertainties. We find an evolution with redshift of the average metallicity of galaxies very similar to those reported in the literature: for a given stellar mass, galaxies at ≈ 1 have, on average, a metallicity ~ 0.3 dex lower than galaxies in the local universe. However we do not see any significant metallicity evolution between redshifts ≈ 0.7 (Paper I) and ≈ ~ 1.0 (this paper). We find also the same flattening of the mass-metallicity relation for the most massive galaxies as reported in Paper I at lower redshifts, but again no apparent evolution of the slope is seen between ≈ ~ 0.7 and ≈ ~ 1.0..