B. R. Granett

The VIMOS Public Extragalactic Redshift Survey (VIPERS) - Galaxy clustering and redshift-space distortions at z ≃ 0.8 in the first data release

We present in this paper the general real- and redshift-space clustering properties of galaxies as measured in the first data release of the VIPERS survey. VIPERS is a large redshift survey designed to probe the distant Universe and its large-scale structure at 0.5 < z < 1.2. We describe in this analysis the global properties of the sample and discuss the survey completeness and associated corrections. This sample allows us to measure the galaxy clustering with an unprecedented accuracy at these redshifts. From the redshift-space distortions observed in the galaxy clustering pattern we provide a first measurement of the growth rate of structure at z = 0.8: f\sigma_8 = 0.47 +/- 0.08. This is completely consistent with the predictions of standard cosmological models based on Einstein gravity, although this measurement alone does not discriminate between different gravity models.

The VIMOS Public Extragalactic Redshift Survey (VIPERS) - A precise measurement of the galaxy stellar mass function and the abundance of massive galaxies at redshifts 0.5 < z < 1.3

We measure the evolution of the galaxy stellar mass function from z = 1.3 to z = 0.5 using the first 53 608 redshifts of the ongoing VIMOS Public Extragalactic Survey (VIPERS). Thanks to its large volume and depth, VIPERS provides a detailed picture of the galaxy distribution at z ≃ 0.8, when the Universe was ≃7 Gyr old. We carefully estimate the uncertainties and systematic effects associated with the SED fitting procedure used to derive galaxy stellar masses. We estimate the galaxy stellar mass function at several epochs between z = 0.5 and 1.3, discussing the amount of cosmic variance affecting our estimate in detail. We find that Poisson noise and cosmic variance of the galaxy mass function in the VIPERS survey are comparable to the statistical uncertainties of large surveys in the local universe. VIPERS data allow us to determine with unprecedented accuracy the high-mass tail of the galaxy stellar mass function, which includes a significant number of galaxies that are too rare to detect with any of the past spectroscopic surveys. At the epochs sampled by VIPERS, massive galaxies had already assembled most of their stellar mass. We compare our results with both previous observations and theoretical models. We apply a photometric classification in the (U − V) rest-frame colour to compute the mass function of blue and red galaxies, finding evidence for the evolution of their contribution to the total number density budget: the transition mass above which red galaxies dominate is found to be about 1010.4 ℳ⊙ at z ≃ 0.55, and it evolves proportionally to (1 + z)3. We are able to separately trace the evolution of the number density of blue and red galaxies with masses above 1011.4 ℳ⊙, in a mass range barely studied in previous work. We find that for such high masses, red galaxies show a milder evolution with redshift, when compared to objects at lower masses. At the same time, we detect a population of similarly massive blue galaxies, which are no longer detectable below z = 0.7. These results show the improved statistical power of VIPERS data, and give initial promising indications of mass-dependent quenching of galaxies at z ≃ 1.

The VIMOS Public Extragalactic Redshift Survey (VIPERS) ⋆ Luminosity and stellar mass dependence of galaxy clustering at 0.5< z< 1.1

Aims. We investigate the dependence of galaxy clustering on luminosity and stellar mass in the redshift range 0.5 < z < 1.1, using the first ~ 55 000 redshifts from the VIMOS Public Extragalactic Redshift Survey (VIPERS). Methods. We measured the redshift-space two-point correlation functions (2PCF), ξ(s) and ξ(rp,π) , and the projected correlation function, wp(rp), in samples covering different ranges of B-band absolute magnitudes and stellar masses. We considered both threshold and binned galaxy samples, with median B-band absolute magnitudes − 21.6 ≲ MB − 5log (h) ≲ − 19.5 and median stellar masses 9.8 ≲ log (M⋆ [h-2 M⊙]) ≲ 10.7. We assessed the real-space clustering in the data from the projected correlation function, which we model as a power law in the range 0.2 < rp [h-1 Mpc ] < 20. Finally, we estimated the galaxy bias as a function of luminosity, stellar mass, and redshift, assuming a flat Λ cold dark matter model to derive the dark matter 2PCF. Results. We provide the best-fit parameters of the power-law model assumed for the real-space 2PCF – the correlation length, r0, and the slope, γ – as well as the linear bias parameter, as a function of the B-band absolute magnitude, stellar mass, and redshift. We confirm and provide the tightest constraints on the dependence of clustering on luminosity at 0.5 < z < 1.1. We prove the complexity of comparing the clustering dependence on stellar mass from samples that are originally flux-limited and discuss the possible origin of the observed discrepancies. Overall, our measurements provide stronger constraints on galaxy formation models, which are now required to match, in addition to local observations, the clustering evolution measured by VIPERS galaxies between z = 0.5 and z = 1.1 for a broad range of luminosities and stellar masses.

Detection of a supervoid aligned with the cold spot of the cosmic microwave background

We use the WISE-2MASS infrared galaxy catalogue matched with Pan-STARRS1 (PS1) galaxies to search for a supervoid in the direction of the cosmic microwave background (CMB) cold spot (CS). Our imaging catalogue has median redshift z ≃ 0.14, and we obtain photometric redshifts from PS1 optical colours to create a tomographic map of the galaxy distribution. The radial profile centred on the CS shows a large low-density region, extending over tens of degrees. Motivated by previous CMB results, we test for underdensities within two angular radii, 5°, and 15°. The counts in photometric redshift bins show significantly low densities at high detection significance, ≳5σ and ≳6σ, respectively, for the two fiducial radii. The line-of-sight position of the deepest region of the void is z ≃ 0.15–0.25. Our data, combined with an earlier measurement by Granett, Szapudi & Neyrinck, are consistent with a large Rvoid = (220 ± 50) h−1 Mpc supervoid with δm ≃ −0.14 ± 0.04 centred at z = 0.22 ± 0.03. Such a supervoid, constituting at least a ≃3.3σ fluctuation in a Gaussian distribution of the Λ cold dark matter model, is a plausible cause for the CS.

The VIMOS Public Extragalactic Redshift Survey (VIPERS): - A quiescent formation of massive red-sequence galaxies over the past 9 Gyr

We explore the evolution of the Colour-Magnitude Relation (CMR) and Luminosity Function (LF) at 0.4 10^11 M_sun) and expeditious RS formation over a short period of ~1.5 Gyr starting before z=1. This is supported by the detection of ongoing SF in ETGs at 0.9<z<1.0, in contrast with the quiescent red stellar populations of ETGs at 0.5<z<0.6. There is an increase in the observed CMR scatter with redshift, two times larger than in galaxy clusters and at variance with theoretical models. We discuss possible physical mechanisms that support the observed evolution of the red galaxy population. Our findings point out that massive galaxies have experienced a sharp SF quenching at z~1 with only limited additional merging. In contrast, less-massive galaxies experience a mix of SF truncation and minor mergers which build-up the low- and intermediate-mass end of the CMR.

Constraints on Massive Neutrinos from the CFHTLS Angular Power Spectrum

We use the galaxy angular power spectrum at z ~ 0.5–1.2 from the Canada-France-Hawaii-Telescope Legacy Survey Wide fields (CFHTLS-Wide) to constrain separately the total neutrino mass ∑mν and the effective number of neutrino species Neff. This survey has recently benefited from an accurate calibration of the redshift distribution, allowing new measurements of the (non-linear) matter power spectrum in a unique range of scales and redshifts sensitive to neutrino free streaming. Our analysis makes use of a recent model for the effect of neutrinos on the weakly non-linear matter power spectrum derived from accurate N-body simulations. We show that CFHTLS, combined with WMAP7 and a prior on the Hubble constant provides an upper limit of ∑mν < 0.29 eV and Neff = 4.17+1.62−1.26 (2 σ confidence levels). If we omit smaller scales which may be affected by non-linearities, these constraints become ∑mν < 0.41 eV and Neff = 3.98+2.02−1.20 (2 σ confidence levels). Finally we show that the addition of other large scale structures probes can further improve these constraints, demonstrating that high redshift large volumes surveys such as CFHTLS are complementary to other cosmological probes of the neutrino mass.

Integrated Sachs-Wolfe Imprint of Superstructures on Linear Scales

We build a model for the density and integrated Sachs-Wolfe (ISW) profile of supervoid and supercluster structures. Our model assumes that fluctuations evolve linearly from an initial Gaussian random field. We find these assumptions capable of describing N-body simulations and simulated ISW maps remarkably well on large scales. We construct an ISW map based on locations of superstructures identified previously in the Sloan Digital Sky Survey Luminous Red Galaxy sample. A matched filter analysis of the cosmic microwave background confirms a signal at the 3.2σ confidence level and estimates the radius of the underlying structures to be 55 ± 28 h –1 Mpc. The amplitude of the signal, however, is 2σ higher than ΛCDM predictions.

The VIMOS Public Extragalactic Redshift Survey (VIPERS) - Environmental effects shaping the galaxy stellar mass function

We exploit the first public data release of VIPERS to investigate environmental effects in galaxy evolution between

The VIMOS Public Extragalactic Redshift Survey (VIPERS) - A support vector machine classification of galaxies, stars, and AGNs

z\sim0.5

The VIMOS Public Extragalactic Redshift Survey - Searching for cosmic voids

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