Modelling the spectra of galaxies at redshift 0.4<z<1.15: the gas physical conditions and the element abundances

Abstract

We revisit the spectra observed by Ramos Almeida et al. (2013) from an homogeneous sample of galaxies at 0.27<z<1.28 with the aim of finding out the characteristics of the single objects by consistent modelling. In particular we investigate the trend of the most significant physical parameters and of the element abundances with redshift. The observed corrected line ratios cover a relatively large range. Nevertheless the calculated physical conditions are similar to those of active galactic nuclei and of starburst galaxies. For some of the galaxies the dominant photoionizing source is ambiguous. The N/H and O/H relative abundances are close to the solar ones but show a dip at z=0.7.