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Abstract:

We present an analysis of the luminosities and equivalent widths of the 284 z < 0.56 [O II]-emitting galaxies found in the 169 arcmin2 pilot survey for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). By combining emission-line fluxes obtained from the Mitchell spectrograph on the McDonald 2.7 m telescope with deep broadband photometry from archival data, we derive each galaxy's dereddened [O II] λ3727 luminosity and calculate its total star formation rate. We show that over the last ∼5 Gyr of cosmic time, there has been substantial evolution in the [O II] emission-line luminosity function, with L* decreasing by ∼0.6 ± 0.2 dex in the observed function, and by ∼0.9 ± 0.2 dex in the dereddened relation. Accompanying this decline is a significant shift in the distribution of [O II] equivalent widths, with the fraction of high equivalent-width emitters declining dramatically with time. Overall, the data imply that the relative intensity of star formation within galaxies has decreased over the past ∼5 Gyr, and that the star formation rate density of the universe has declined by a factor of ∼2.5 between z ∼ 0.5 and z ∼ 0. These observations represent the first [O II]-based star formation rate density measurements in this redshift range, and foreshadow the advancements which will be generated by the main HETDEX survey. © 2013. The American Astronomical Society. All rights reserved.

Abstract:

© 2013, Springer Science+Business Media Dordrecht. We report on HiZELS, the High-z Emission Line Survey, our successful panoramic narrow-band campaign survey using WFCAM on UKIRT to detect and study emission line galaxies at z ∼ 1–9. HiZELS employs the H 2 (S1) narrow-band filter together with custom-made narrow-band filters in the J and H-bands, with the primary aim of delivering large identically-selected samples of Hα emitting galaxies at redshifts of 0.84, 1.47 and 2.23. Comparisons between the luminosity function, the host galaxy properties, the clustering, and the variation with environment of these Hα-selected samples are yielding unique constraints on the nature and evolution of star-forming galaxies, across the peak epoch of star formation activity in the Universe. We provide a summary of the project status, and detail the main scientific results obtained so far: the measurement of the evolution of the cosmic star formation rate density out to z < 2 using a single star formation indicator, determination of the morphologies, environments and dust content of the star-forming galaxies, and a detailed investigation of the evolution of their clustering properties. We also summarise the on-going work and future goals of the project.