The metallicity evolution of blue compact dwarf galaxies from the intermediate redshift to the local Universe

TL;DR

This study compares the metallicity, star formation, and age indicators of blue compact dwarf galaxies at intermediate redshift and in the local universe, revealing minimal evolution in key relations and suggesting universality in their properties.

Contribution

It provides the first comprehensive comparison of metallicity and related properties of BCDs across redshift, indicating stable relations and offering constraints for galaxy evolution models.

Findings

Intermediate-z BCDs have higher R23 ratios than local BCDs.

No significant difference in the mass-metallicity relation between the two samples.

Intermediate-z BCDs are younger, with lower D4000 indices.

Abstract

We present oxygen abundance measurements for 74 blue compact dwarf (BCD) galaxies in the redshift range in [0.2, 0.5] using the strong-line method. The spectra of these objects are taken using Hectospec on the Multiple Mirror Telescope (MMT). More than half of these BCDs had dust attenuation corrected using the Balmer decrement method. For comparison, we also selected a sample of 2023 local BCDs from the Sloan Digital Sky Survey (SDSS) database. Based on the local and intermediate-z BCD samples, we investigated the cosmic evo- lution of the metallicity, star-formation rate (SFR), and Dn (4000) index. Com- pared with local BCDs, the intermediate-z BCDs had a systematically higher R23 ratio but similar O32 ratio. Interestingly, no significant deviation in the mass-metallicity (MZ) relation was found between the intermediate-z and lo- cal BCDs. Besides the metallicity, the intermediate-z BCDs also exhibited an SFR distribution that was consistent with local BCDs, suggesting a weak de- pendence on redshift. The intermediate-z BCDs seemed to be younger than the local BCDs with lower D4000 index values. The insignificant deviation in the mass-metallicity and mass-SFR relations between intermediate-z and local BCDs indicates that the relations between the global parameters of low-mass compact galaxies may be universal. These results from low mass compact galaxies could be used to place important observational constraints on galaxy formation and evolution models.