The WiggleZ Dark Energy Survey: Final Data Release and the Metallicity of UV-Luminous Galaxies

TL;DR

This paper presents the final data release of the WiggleZ Dark Energy Survey, analyzing UV-luminous galaxies' emission lines and metallicities, revealing unique properties of high-mass galaxies with lower metallicities than typical emission-line galaxies.

Contribution

The study provides the final WiggleZ galaxy catalog, detailed spectral analysis, and new insights into the metallicity properties of UV-luminous galaxies across different masses.

Findings

High-mass WiggleZ galaxies have lower metallicities than normal galaxies at the same mass.

Broad H-beta emission indicates active nuclei and gas outflows in luminous galaxies.

Metallicity does not vary with redshift, suggesting a property specific to UV-luminous galaxies.

Abstract

The WiggleZ Dark Energy Survey measured the redshifts of over 200,000 UV-selected (NUV<22.8 mag) galaxies on the Anglo-Australian Telescope. The survey detected the baryon acoustic oscillation signal in the large scale distribution of galaxies over the redshift range 0.2<z<1.0, confirming the acceleration of the expansion of the Universe and measuring the rate of structure growth within it. Here we present the final data release of the survey: a catalogue of 225415 galaxies and individual files of the galaxy spectra. We analyse the emission-line properties of these UV-luminous Lyman-break galaxies by stacking the spectra in bins of luminosity, redshift, and stellar mass. The most luminous (-25 mag < MFUV <-22 mag) galaxies have very broad H-beta emission from active nuclei, as well as a broad second component to the [OIII] (495.9 nm, 500.7 nm) doublet lines that is blue shifted by 100 km/s, indicating the presence of gas outflows in these galaxies. The composite spectra allow us to detect and measure the temperature-sensitive [OIII] (436.3 nm) line and obtain metallicities using the direct method. The metallicities of intermediate stellar mass (8.8<log(M*/Msun)<10) WiggleZ galaxies are consistent with normal emission-line galaxies at the same masses. In contrast, the metallicities of high stellar mass (10<log(M*/Msun)<12) WiggleZ galaxies are significantly lower than for normal emission-line galaxies at the same masses. This is not an effect of evolution as the metallicities do not vary with redshift; it is most likely a property specific to the extremely UV-luminous WiggleZ galaxies.