We present the ultraviolet (UV) luminosity function of galaxies from the GALEX Medium Imaging Survey with measured spectroscopic redshifts from the first data release of the WiggleZ Dark Energy ...Survey. Our sample consists of 39 996 NUV < 22.8 emission line galaxies in the redshift range 0.1 < z < 0.9. This sample selects galaxies with high star formation rates: at 0.6 < z < 0.9 the median star formation rate is at the upper 95th percentile of optically selected (r < 22.5) galaxies and the sample contains about 50 per cent of all NUV < 22.8, 0.6 < z < 0.9 starburst galaxies within the volume sampled. The most luminous galaxies in our sample ( − 21.0 > M
NUV > −22.5) evolve very rapidly with a number density declining as (1 + z)5±1 from redshift z = 0.9 to 0.6. These starburst galaxies (M
NUV < −21 is approximately a star formation rate of 30 M yr−1) contribute about 1 per cent of cosmic star formation over the redshift range z = 0.6-0.9. The star formation rate density of these very luminous galaxies evolves rapidly, as (1 + z)4±1. Such a rapid evolution implies that the majority of star formation in these large galaxies must have occurred before z = 0.9. We measure the UV luminosity function in Δz = 0.05 redshift intervals spanning 0.1 < z < 0.9, and provide analytic fits to the results. Our measurements of the luminosity function over this redshift range probe further into the bright end (1-2 mag further) than previous measurements, e.g. Arnouts et al., Budavári et al. and Treyer et al., due to our much larger sample size and sampled volume. At all redshifts z > 0.55 we find that the bright end of the luminosity function is not well described by a pure Schechter function due to an excess of very luminous (M
NUV < −22) galaxies. These luminosity functions can be used to create a radial selection function for the WiggleZ survey or test models of galaxy formation and evolution. Here we test the AGN feedback model in Scannapieco, Silk & Bouwens, and find that this AGN feedback model requires AGN feedback efficiency to vary with one or more of the following: stellar mass, star formation rate and redshift.
The WiggleZ Dark Energy Survey is a large-scale structure survey of intermediate-redshift ultraviolet-selected (UV-selected) emission-line galaxies scheduled to cover 1000 deg2, spanning a broad ...redshift range 0.2 < z < 1.0. The main scientific goal of the survey is the measurement of baryon acoustic oscillations (BAO) in the galaxy clustering pattern at a significantly higher redshift than previous studies. The BAO may be applied as a standard cosmological ruler to constrain dark energy models. Based on the first 20 per cent of the data set, we present initial results concerning the small-scale clustering of the WiggleZ targets, together with survey forecasts. The WiggleZ galaxy population possesses a clustering length r0= 4.40 ± 0.12 h−1 Mpc, which is significantly larger than z= 0 UV-selected samples, with a slope γ= 1.92 ± 0.08. This clustering length is comparable to z= 3 Lyman-break galaxies with similar UV luminosities. The clustering strength of the sample increases with optical luminosity, UV luminosity and reddening rest-frame colour. The full survey, scheduled for completion in 2010, will map an effective volume Veff≈ 1 Gpc3 (evaluated at a scale k= 0.15 h Mpc−1) and will measure the angular diameter distance and Hubble expansion rates in three redshift bins with accuracies of ≈5 per cent. We will determine the value of a constant dark energy equation-of-state parameter, wcons, with a higher precision than existing supernovae observations using an entirely independent technique. The WiggleZ and supernova measurements lie in highly complementary directions in the plane of wcons and the matter density Ωm. The forecast using the full combination of WiggleZ, supernova and cosmic microwave background (CMB) data sets is a marginalized error Δwcons= 0.07, providing a robust and precise measurement of the properties of dark energy including cross-checking of systematic errors.
We characterize the stellar masses and star formation rates in a sample of ~40 000 spectroscopically confirmed UV-luminous galaxies at 0.3 < z < 1.0 selected from within the WiggleZ Dark Energy ...Survey. In particular, we match this UV bright population to wide-field infrared surveys such as the near-infrared (NIR) UKIDSS Large Area Survey (LAS) and the mid-infrared Wide-Field Infrared Survey Explorer (WISE) All-Sky Survey. We find that ~30 per cent of the UV-luminous WiggleZ galaxies, corresponding to the brightest and reddest subset, are detected at >5... in the UKIDSS-LAS at all redshifts. An even more luminous subset of 15 per cent are also detected in the WISE 3.4 and 4.6 ...m bands. In addition, 22 of the WiggleZ galaxies are extremely luminous at 12 and 22 ...m and have colours consistent with being star formation dominated. We compute stellar masses for this very large sample of extremely blue galaxies and quantify the sensitivity of the stellar mass estimates to various assumptions made during the spectral energy distribution (SED) fitting. The median stellar masses are log10(M*/M...) = 9.6 ± 0.7, 10.2 ± 0.5 and 10.4 ± 0.4 for the IR undetected, UKIDSS detected and UKIDSS+WISE detected galaxies, respectively. We demonstrate that the inclusion of NIR photometry can lead to tighter constraints on the stellar masses by bringing down the upper bound on the stellar mass estimate. The mass estimates are found to be most sensitive to the inclusion of secondary bursts of star formation as well as changes in the stellar population synthesis models, both of which can lead to median discrepancies of the order of 0.3...dex in the stellar masses. We conclude that even for these extremely blue galaxies, different SED fitting codes therefore produce extremely robust stellar mass estimates. We find, however, that the best-fitting M/L... is significantly lower than that predicted by simple optical colour-based estimators for many of the WiggleZ galaxies. The simple colour-based estimator overpredicts M/L... by ~0.4...dex on average. The effect is more pronounced for bluer galaxies with younger best-fitting ages. The WiggleZ galaxies have star formation rates of 3-10 M... yr... and mostly lie at the upper end of the main sequence of star-forming galaxies at these redshifts. Their rest-frame UV luminosities and stellar masses are comparable to both local compact UV-luminous galaxies as well as Lyman break galaxies at z ~ 2-3. The stellar masses from this paper will be made publicly available with the next WiggleZ data release. (ProQuest: ... denotes formulae/symbols omitted.)
We study the evolution of galaxy populations around the spectroscopic WiggleZ sample of star-forming galaxies at 0.25 < or =, slant z < or =, slant 0.75 using the photometric catalog from the Second ...Red-Sequence Cluster Survey (RCS2). We probe the optical photometric properties of the net excess neighbor galaxies. The key concept is that the marker galaxies and their neighbors are located at the same redshift, providing a sample of galaxies representing a complete census of galaxies in the neighborhood of star-forming galaxies. The results are compared with those using the RCS WiggleZ Spare-Fibre (RCS-WSF) sample as markers, representing galaxies in cluster environments at 0.25 < or =, slant z < or =, slant 0.45. By analyzing the stacked color-color properties of the WiggleZ neighbor galaxies, we find that their optical colors are not a strong function of indicators of star-forming activities such as EW(OII) or Galaxy Evolution Explorer (GALEX) near-UV luminosity of the markers. The galaxies around the WiggleZ markers exhibit a bimodal distribution on the color-magnitude diagram, with most of them located in the blue cloud. The optical galaxy luminosity functions (GLFs) of the blue neighbor galaxies have a faint-end slope alpha of ~ -1.3, similar to that for galaxies in cluster environments drawn from the RCS-WSF sample. The faint-end slope of the GLF for the red neighbors, however, is ~ -0.4, significantly shallower than the ~ -0.7 found for those in cluster environments. This suggests that the buildup of the faint end of the red sequence in cluster environments is in a significantly more advanced stage than that in the star-forming and lower galaxy density WiggleZ neighborhoods. We find that the red galaxy fraction (functionof sub(red)) around the star-forming WiggleZ galaxies has similar values from z ~ 0.3 to z ~ 0.6 with functionof sub(red) ~ 0.28, but drops to functionof sub(red) ~ 0.20 at z > ~0.7. This change of functionof sub(red) with redshift suggests that there is either a higher rate of star-forming galaxies entering the luminosity-limited sample at z > ~0.7, or a decrease in the quenching rate of star formation at that redshift. Comparing to that in a dense cluster environment, the functionof sub(red) of the WiggleZ neighbors is both considerably smaller and has a more moderate change with redshift, pointing to the stronger and more prevalent environmental influences on galaxy evolution in high-density regions.
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