Open AccessChemical abundances in a UV‐selected sample of galaxies
Author(s) -
Contini Thierry,
Treyer Marie A.,
Sullivan Mark,
Ellis Richard S.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05042.x
Subject(s) - physics , astrophysics , galaxy , metallicity , redshift , star formation , astronomy , galaxy formation and evolution , abundance of the chemical elements , luminous infrared galaxy , stars , context (archaeology) , paleontology , biology
We discuss the chemical properties of a sample of UV‐selected intermediate‐redshift (0≲z≲0.4) galaxies in the context of their physical nature and star‐formation history. This work represents an extension of our previous studies of the rest‐frame UV‐luminosity function (Treyer et al.) and the star‐formation properties of the same sample (Sullivan et al.). We revisit the optical spectra of these galaxies and perform further emission‐line measurements restricting the analysis to those spectra with the full set of emission lines required to derive chemical abundances. Our final sample consists of 68 galaxies with heavy‐element abundance ratios and both UV and CCD B ‐band photometry. Diagnostics based on emission‐line ratios show that all but one of the galaxies in our sample are powered by hot, young stars rather than by an AGN. Oxygen‐to‐hydrogen (O/H) and nitrogen‐to‐oxygen (N/O) abundance ratios are compared with those of various local and intermediate‐redshift samples. Our UV‐selected galaxies span a wide range of oxygen abundances, from ∼0.1 to 1 Z ⊙ , intermediate between low‐mass H ii galaxies and massive starburst nuclei. For a given oxygen abundance, most have strikingly low N/O values. Moreover, UV‐selected and H ii galaxies systematically deviate from the usual metallicity–luminosity relation in the sense of being more luminous by 2–3 mag . Adopting the ‘delayed‐release’ chemical evolution model, we propose our UV‐selected sources are observed at a special stage in their evolution, following a powerful starburst that enriched their ISM in oxygen and temporarily lowered their mass‐to‐light ratios. We discuss briefly the implications of our conclusions on the nature of similarly selected high‐redshift galaxies.