Abstract
We perform a joint determination of the distance-redshift relation and cosmic expansion rate at redshifts z = 0.44, 0.6 and 0.73 by combining measurements of the baryon acoustic peak and ...Alcock-Paczynski distortion from galaxy clustering in the WiggleZ Dark Energy Survey, using a large ensemble of mock catalogues to calculate the covariance between the measurements. We find that D
A(z) = (1205 ± 114, 1380 ± 95, 1534 ± 107) Mpc and H(z) = (82.6 ± 7.8, 87.9 ± 6.1, 97.3 ± 7.0) km s−1 Mpc−1 at these three redshifts. Further combining our results with other baryon acoustic oscillation and distant supernovae data sets, we use a Monte Carlo Markov Chain technique to determine the evolution of the Hubble parameter H(z) as a stepwise function in nine redshift bins of width Δz = 0.1, also marginalizing over the spatial curvature. Our measurements of H(z), which have precision better than 7 per cent in most redshift bins, are consistent with the expansion history predicted by a cosmological constant dark energy model, in which the expansion rate accelerates at redshift z < 0.7.
We present significant improvements in cosmic distance measurements from the WiggleZ Dark Energy Survey, achieved by applying the reconstruction of the baryonic acoustic feature technique. We show ...using both data and simulations that the reconstruction technique can often be effective despite patchiness of the survey, significant edge effects and shot-noise. We investigate three redshift bins in the redshift range 0.2 < z < 1, and in all three find improvement after reconstruction in the detection of the baryonic acoustic feature and its usage as a standard ruler. We measure model-independent distance measures D
V(r
s
fid/r
s) of 1716 ± 83, 2221 ± 101, 2516 ± 86 Mpc (68 per cent CL) at effective redshifts z = 0.44, 0.6, 0.73, respectively, where D
V is the volume-averaged distance, and r
s is the sound horizon at the end of the baryon drag epoch. These significantly improved 4.8, 4.5 and 3.4 per cent accuracy measurements are equivalent to those expected from surveys with up to 2.5 times the volume of WiggleZ without reconstruction applied. These measurements are fully consistent with cosmologies allowed by the analyses of the Planck Collaboration and the Sloan Digital Sky Survey. We provide the D
V(r
s
fid/r
s) posterior probability distributions and their covariances. When combining these measurements with temperature fluctuations measurements of Planck, the polarization of Wilkinson Microwave Anisotropy Probe 9, and the 6dF Galaxy Survey baryonic acoustic feature, we do not detect deviations from a flat Λ cold dark matter (ΛCDM) model. Assuming this model, we constrain the current expansion rate to H
0 = 67.15 ± 0.98 km s−1Mpc−1. Allowing the equation of state of dark energy to vary, we obtain w
DE = −1.080 ± 0.135. When assuming a curved ΛCDM model we obtain a curvature value of ΩK = −0.0043 ± 0.0047.
We present measurements of the baryon acoustic peak at redshifts z= 0.44, 0.6 and 0.73 in the galaxy correlation function of the final data set of the WiggleZ Dark Energy Survey. We combine our ...correlation function with lower redshift measurements from the 6-degree Field Galaxy Survey and Sloan Digital Sky Survey, producing a stacked survey correlation function in which the statistical significance of the detection of the baryon acoustic peak is 4.9σ relative to a zero-baryon model with no peak. We fit cosmological models to this combined baryon acoustic oscillation (BAO) data set comprising six distance-redshift data points, and compare the results with similar cosmological fits to the latest compilation of supernovae (SNe) and cosmic microwave background (CMB) data. The BAO and SNe data sets produce consistent measurements of the equation-of-state w of dark energy, when separately combined with the CMB, providing a powerful check for systematic errors in either of these distance probes. Combining all data sets we determine w=−1.03 ± 0.08 for a flat universe, consistent with a cosmological constant model. Assuming dark energy is a cosmological constant and varying the spatial curvature, we find Ωk=−0.004 ± 0.006.
The growth history of large-scale structure in the Universe is a powerful probe of the cosmological model, including the nature of dark energy. We study the growth rate of cosmic structure to ...redshift z = 0.9 using more than 162 000 galaxy redshifts from the WiggleZ Dark Energy Survey. We divide the data into four redshift slices with effective redshifts z = 0.2, 0.4, 0.6, 0.76 and in each of the samples measure and model the two-point galaxy correlation function in parallel and transverse directions to the line of sight. After simultaneously fitting for the galaxy bias factor we recover values for the cosmic growth rate which are consistent with our assumed Λcold dark matter (ΛCDM) input cosmological model, with an accuracy of around 20 per cent in each redshift slice. We investigate the sensitivity of our results to the details of the assumed model and the range of physical scales fitted, making close comparison with a set of N-body simulations for calibration. Our measurements are consistent with an independent power-spectrum analysis of a similar data set, demonstrating that the results are not driven by systematic errors. We determine the pairwise velocity dispersion of the sample in a non-parametric manner, showing that it systematically increases with decreasing redshift, and investigate the Alcock-Paczynski effects of changing the assumed fiducial model on the results. Our techniques should prove useful for current and future galaxy surveys mapping the growth rate of structure using the two-dimensional correlation function.
Approximately half of the nearby E+A galaxies followed up with 21-cm observations have detectable H i emission. The optical spectra of these galaxies show strong post-starburst stellar populations ...but no optical emission lines implying star formation is not ongoing despite the presence of significant gas reservoirs. We have obtained integral field spectroscopic follow-up observations of the two brightest, and nearest, of the six E+A galaxies with H i 21-cm emission in the recent sample of Zwaan et al. In the central regions of both galaxies, the observations are consistent with a post-starburst population with little emission. However, outside the central regions both galaxies have strong optical emission lines, with a clumpy or knot-like distribution, indicating ongoing star formation. We conclude that in these two cases, the presence of optical spectra lacking evidence for star formation while a large gas mass is present can be explained by an aperture effect in selecting the nearby E+A galaxies using single-fibre spectroscopy that probes only the galaxy core.
Abstract
The WiggleZ Dark Energy Survey measured the redshifts of over 200 000 ultraviolet (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 225 415 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 ($-25 \rm \, mag<M_{\rm FUV}<-22 \rm \, mag$) galaxies have very broad Hβ emission from active nuclei, as well as a broad second component to the O iii (495.9 nm, 500.7 nm) doublet lines that is blueshifted by 100 km s−1 , indicating the presence of gas outflows in these galaxies. The composite spectra allow us to detect and measure the temperature-sensitive O iii (436.3 nm) line and obtain metallicities using the direct method. The metallicities of intermediate stellar mass (8.8 < log (M*/M⊙) < 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*/M⊙) < 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.
We explore the radial distribution of star formation in galaxies in the SAMI Galaxy Survey as a function of their local group environment. Using a sample of galaxies in groups (with halo masses less ...than \( \simeq 10^{14} \, \mathrm{M_{\odot}}\)) from the Galaxy And Mass Assembly Survey, we find signatures of environmental quenching in high-mass groups (\(M_{G} > 10^{12.5} \, \mathrm{M_{\odot}}\)). The mean integrated specific star formation rate of star-forming galaxies in high-mass groups is lower than for galaxies in low-mass groups or that are ungrouped, with \(\Delta \log(sSFR/\mathrm{yr^{-1}}) = 0.45 \pm 0.07\). This difference is seen at all galaxy stellar masses. In high-mass groups, star-forming galaxies more massive than \(M_{*} \sim 10^{10} \, \mathrm{M_{\odot}}\) have centrally-concentrated star formation. These galaxies also lie below the star-formation main sequence, suggesting they may be undergoing outside-in quenching. Lower mass galaxies in high-mass groups do not show evidence of concentrated star formation. In groups less massive than \(M_{G} = 10^{12.5} \, \mathrm{M_{\odot}}\) we do not observe these trends. In this regime we find a modest correlation between centrally-concentrated star formation and an enhancement in total star formation rate, consistent with triggered star formation in these galaxies.
We present results from the 2D anisotropic baryon acoustic oscillation (BAO) signal present in the final data set from the WiggleZ Dark Energy Survey. We analyse the WiggleZ data in two ways: first ...using the full shape of the 2D correlation function and secondly focusing only on the position of the BAO peak in the reconstructed data set. When fitting for the full shape of the 2D correlation function we use a multipole expansion to compare with theory. When we use the reconstructed data we marginalize over the shape and just measure the position of the BAO peak, analysing the data in wedges separating the signal along the line of sight from that parallel to the line of sight. We verify our method with mock data and find the results to be free of bias or systematic offsets. We also redo the pre-reconstruction angle-averaged (1D) WiggleZ BAO analysis with an improved covariance and present an updated result. The final results are presented in the form of Ω
,
(
), and
(
) for three redshift bins with effective redshifts
= 0.44, 0.60, and 0.73. Within these bins and methodologies, we recover constraints between 5 and 22 per cent error. Our cosmological constraints are consistent with flat ΛCDM cosmology and agree with results from the Baryon Oscillation Spectroscopic Survey.
The absolute neutrino mass scale is currently unknown, but can be constrained by cosmology. The WiggleZ high redshift, star-forming, and blue galaxy sample offers a complementary data set to previous ...surveys for performing these measurements, with potentially different systematics from nonlinear structure formation, redshift-space distortions, and galaxy bias. We obtain a limit of capital sigma m sub(nu) < 0.60 eV (95% confidence) for WiggleZ + Wilkinson Microwave Anisotropy Probe. Combining with priors on the Hubble parameter and the baryon acoustic oscillation scale gives capital sigma m sub(nu) < 0.29 eV, which is the strongest neutrino mass constraint derived from spectroscopic galaxy redshift surveys.
We study the environments of low- and high- excitation radio galaxies (LERGs and HERGs respectively) in the redshift range \(0.01 < z < 0.4\), using a sample of 399 radio galaxies and environmental ...measurements from the Galaxy And Mass Assembly (GAMA) survey. In our analysis we use the fifth nearest neighbour density (\(\Sigma_{5}\)) and the GAMA galaxy groups catalogue (G3Cv6) and construct control samples of galaxies matched in {\update stellar mass and colour} to the radio-detected sample. We find that LERGs and HERGs exist in different environments and that this difference is dependent on radio luminosity. High-luminosity LERGs (\(L_{\rm NVSS} \gtrsim 10^{24}\) W Hz\(^{-1}\)) lie in much denser environments than a matched radio-quiet control sample (about three times as dense, as measured by \(\Sigma_{5}\)), and are more likely to be members of galaxy groups (\(82^{+5}_{-7}\) percent of LERGs are in GAMA groups, compared to \(58^{+3}_{-3}\) percent of the control sample). In contrast, the environments of the HERGs and lower luminosity LERGs are indistinguishable from that of a matched control sample. Our results imply that high-luminosity LERGs lie in more massive haloes than non-radio galaxies of similar stellar mass and colour, in agreement with earlier studies (Wake et al. 2008; Donoso et al. 2010). When we control for the preference of LERGs to be found in groups, both high- and low- luminosity LERGs are found in higher-mass haloes (\(\sim 0.2\) dex; at least 97 percent significant) than the non-radio control sample.
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