The nitrogen and oxygen abundances in the neutral gas at high redshift

Abstract

Aims.We study the oxygen and nitrogen abundances in the interstellar medium of high-redshift galaxies.Methods.We use high resolution and high signal-to-noise ratio spectra of damped Lyman-α (DLA) systems detected along the line-of-sight to quasars to derive robust abundance measurements from unsaturated metal absorption lines.Results.We present results for a sample of 16 high-redshift DLAs and strong sub-DLAs (log (H I) > 19.5, 2.4 < < 3.6) including 13 new measurements. We find that the oxygen to iron abundance ratio is pretty much constant with [O/Fe] ~ +0.320.10 for -2.5