Aims. We trace the evolution and the star formation history of passive red galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). The detailed spectral analysis of ...stellar populations of intermediate-redshift passive red galaxies allows the build up of their stellar content to be followed over the last 8 billion years. Methods. We extracted a sample of passive red galaxies in the redshift range 0.4 <z< 1.0 and stellar mass range 10 < log (Mstar/M⊙) < 12 from the VIPERS survey. The sample was selected using an evolving cut in the rest-frame U−V color distribution and additional cuts that ensured high quality. The spectra of passive red galaxies were stacked in narrow bins of stellar mass and redshift. We use the stacked spectra to measure the 4000 Å break (D4000) and the Hδ Lick index (HδA) with high precision. These spectral features are used as indicators of the star formation history of passive red galaxies. We compare the results with a grid of synthetic spectra to constrain the star formation epochs of these galaxies. We characterize the formation redshift-stellar mass relation for intermediate-redshift passive red galaxies. Results. We find that at z ~ 1 stellar populations in low-mass passive red galaxies are younger than in high-mass passive red galaxies, similar to what is observed at the present epoch. Over the full analyzed redshift range 0.4 < z < 1.0 and stellar mass range 10 < log (Mstar/M⊙) < 12, the D4000 index increases with redshift, while HδA gets lower. This implies that the stellar populations are getting older with increasing stellar mass. Comparison to the spectra of passive red galaxies in the SDSS survey (z ~ 0.2) shows that the shape of the relations of D4000 and HδA with stellar mass has not changed significantly with redshift. Assuming a single burst formation, this implies that high-mass passive red galaxies formed their stars at zform ~ 1.7, while low-mass galaxies formed their main stellar populations more recently, at zform ~ 1. The consistency of these results, which were obtained using two independent estimators of the formation redshift (D4000 and HδA), further strengthens a scenario in which star formation proceeds from higher to lower mass systems as time passes, i.e., what has become known as the downsizing picture.
We explore the evolution of the statistical distribution of galaxy morphological properties and colours over the redshift range 0.5 < z < 1, combining high-quality imaging data from the CFHT Legacy ...Survey with the large number of redshifts and extended photometry from the VIPERS survey. Galaxy structural parameters are measured by fitting S\'ersic profiles to i-band images and then combined with absolute magnitudes, colours and redshifts, to trace the evolution in a multi-parameter space. We analyse, using a new method, the combination of colours and structural parameters of early- and late-type galaxies in luminosity--redshift space. We found that both the rest-frame colour distributions in the (U-B) vs. (B-V) plane and the S\'ersic index distributions are well fitted by a sum of two Gaussians, with a remarkable consistency of red-spheroidal and blue-disky galaxy populations, over the explored redshift (0.5 < z <1) and luminosity (−1.5 < B−B∗ < 1.0) ranges. The combination of the UBV rest-frame colour and S\'ersic index n as a function of redshift and luminosity allows us to present the structure of early- and late-type galaxies and their evolution. We found that early type galaxies display only a slow change of their concentrations since z∼1; it is already established by z∼1 and depends much more strongly on their luminosities. In contrast, late-type galaxies get clearly more concentrated with cosmic time since z∼1, with only little evolution in colour, which remains dependent mainly on their luminosity. This flipped luminosity (mass) and redshift dependence likely reflects different evolutionary tracks of early- and late-type galaxies before and after z∼1. The combination of rest-frame colours and S\'ersic index n as a function of redshift and luminosity leads to a precise statistical description of the structure of galaxies and their evolution.
We exploit the first public data release of VIPERS to investigate environmental effects in the evolution of galaxies between z ~ 0.5 and 0.9. The large number of spectroscopic redshifts (more than 50 ...000) over an area of about 10 deg2 provides a galaxy sample with high statistical power. The accurate redshift measurements (σz = 0.00047(1 + zspec)) allow us to robustly isolate galaxies living in the lowest and highest density environments (δ< 0.7 and δ> 4, respectively) as defined in terms of spatial 3D density contrast δ. We estimate the stellar mass function of galaxies residing in these two environments and constrain the high-mass end (ℳ ≳ 1011 ℳ⊙) with unprecedented precision. We find that the galaxy stellar mass function in the densest regions has a different shape than was measured at low densities, with an enhancement of massive galaxies and a hint of a flatter (less negative) slope at z< 0.8. We normalise each mass function to the comoving volume occupied by the corresponding environment and relate estimates from different redshift bins. We observe an evolution of the stellar mass function of VIPERS galaxies in high densities, while the low-density one is nearly constant. We compare these results to semi-analytical models and find consistent environmental signatures in the simulated stellar mass functions. We discuss how the halo mass function and fraction of central/satellite galaxies depend on the environments considered, making intrinsic and environmental properties of galaxies physically coupled, hence difficult to disentangle. The evolution of our low-density regions is described well by the formalism introduced by Peng et al. (2010, ApJ, 721, 193), and is consistent with the idea that galaxies become progressively passive because of internal physical processes. The same formalism could also describe the evolution of the mass function in the high density regions, but only if a significant contribution from dry mergers is considered.
Aims. Using the VIMOS Public Extragalactic Redshift Survey (VIPERS) we aim to jointly estimate the keyparameters that describe the galaxy density field and its spatial correlations in redshift space. ...Methods. We use the Bayesian formalism to jointly reconstruct the redshift-space galaxy density field, power spectrum, galaxy bias and galaxy luminosity function given the observations and survey selection function. The high-dimensional posterior distribution is explored using the Wiener filter within a Gibbs sampler. We validate the analysis using simulated catalogues and apply it to VIPERS data taking into consideration the inhomogeneous selection function. Results. We present joint constraints on the anisotropic power spectrum, and the bias and number density of red and blue galaxy classes in luminosity and redshift bins as well as the measurement covariances of these quantities. We find that the inferred galaxy bias and number density parameters are strongly correlated although they are only weakly correlated with the galaxy power spectrum. The power spectrum and redshift-space distortion parameters are in agreement with previous VIPERS results with the value of the growth rate fσ8 = 0.38 with 18% uncertainty at redshift 0.7.
Future data provided by the Euclid mission will allow us to better understand the cosmic history of the Universe. A metric of its performance is the figure-of-merit (FoM) of dark energy, usually ...estimated with Fisher forecasts. The expected FoM has previously been estimated taking into account the two main probes of Euclid, namely the three-dimensional clustering of the spectroscopic galaxy sample, and the so-called 3×2 pt signal fromthe photometric sample (i.e., the weak lensing signal, the galaxy clustering, and their cross-correlation). So far, these two probes have been treated as independent. In this paper, we introduce a new observable given by the ratio of the (angular) two-point correlation function of galaxies from the two surveys. For identical (normalised) selection functions, this observable is unaffected by sampling noise, and its variance is solely controlled byPoisson noise. We present forecasts for Euclid where this multi-tracer method is applied and is particularly relevant because the two surveys will cover the same area of the sky. This method allows for the exploitation of the combination of the spectroscopic and photometric samples. When the correlation between this new observable and the other probes is not taken into account, a significant gain is obtained in the FoM, as well as inthe constraints on other cosmological parameters. The benefit is more pronounced for a commonly investigated modified gravity model, namely the γ parametrisation of the growth factor. However, the correlation between the different probes is found to be significant and hence the actual gain is uncertain. We present various strategies for circumventing this issue and still extract useful information from the new observable.
We explore the evolution of the colour-magnitude relation (CMR) and luminosity function (LF) at 0.4 < zeta < 1.3 from the VIMOS Public Extragalactic Redshift Survey (VIPERS) using similar45000 ...galaxies with precise spectroscopic redshifts down to (ProQuest: Formulae and/or non-USASCII text omitted) over similar10.32 degsup 2 in two fields. From zeta = 0.5 to zeta = 1.3 the LF and CMR are well defined for different galaxy populations and (ProQuest: Formulae and/or non-USASCII text omitted) evolves by similar1.04(1.09) + or - 0.06(0.10) mag for the total (red) galaxy sample. Our findings point out that massive galaxies have experienced a sharp SF quenching at zeta similar 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.
Context. The characterisation of cosmic voids gives unique information about the large-scale distribution of galaxies, their evolution, and thecosmological model. Aims. We identify and characterise ...cosmic voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS) at redshift 0.55 <z< 0.9. Methods. A new void search method is developed based upon the identification of empty spheres that fit between galaxies. The method can be used to characterise the cosmic voids despite the presence of complex survey boundaries and internal gaps. We investigate the impact of systematic observational effects and validate the method against mock catalogues. We measure the void size distribution and the void-galaxy correlation function. Results. We construct a catalogue of voids in VIPERS. The distribution of voids is found to agree well with the distribution of voids found in mock catalogues. The void-galaxy correlation function shows indications of outflow velocity from the voids.
We describe the construction and general features of VIPERS, the VIMOS Public Extragalactic Redshift Survey. This ESO Large Programme is using the Very Large Telescope with the aim of building a ...spectroscopic sample of ~ 100 000 galaxies with iAB< 22.5 and 0.5 <z< 1.5. The survey covers a total area of ~ 24 deg2 within the CFHTLS-Wide W1 and W4 fields. VIPERS is designed to address a broad range of problems in large-scale structure and galaxy evolution, thanks to a unique combination of volume (~ 5 × 107h-3 Mpc3) and sampling rate (~ 40%), comparable to state-of-the-art surveys of the local Universe, together with extensive multi-band optical and near-infrared photometry. Here we present the survey design, the selection of the source catalogue and the development of the spectroscopic observations. We discuss in detail the overall selection function that results from the combination of the different constituents of the project. This includes the masks arising from the parent photometric sample and the spectroscopic instrumental footprint, together with the weights needed to account for the sampling and the success rates of the observations. Using the catalogue of 53 608 galaxy redshifts composing the forthcoming VIPERS Public Data Release 1 (PDR-1), we provide a first assessment of the quality of the spectroscopic data. The stellar contamination is found to be only 3.2%, endorsing the quality of the star–galaxy separation process and fully confirming the original estimates based on the VVDS data, which also indicate a galaxy incompleteness from this process of only 1.4%. Using a set of 1215 repeated observations, we estimate an rms redshift error σz/ (1 + z) = 4.7 × 10-4 and calibrate the internal spectral quality grading. Benefiting from the combination of size and detailed sampling of this dataset, we conclude by presenting a map showing in unprecedented detail the large-scale distribution of galaxies between 5 and 8 billion years ago.
We use a sample of about 22 000 galaxies at 0.65 < z < 1.2 from the VIMOS Public Extragalactic Redshift Survey (VIPERS) Public Data Release 1 (PDR-1) catalogue, to constrain the cosmological model ...through a measurement of the galaxy clustering ratio ηg,R. This statistic has favourable properties, which is defined as the ratio of two quantities characterizing the smoothed density field in spheres of a given radius R: the value of its correlation function on a multiple of this scale, ξ(nR), and its variance σ2(R). For sufficiently large values of R, this is a universal number, which captures 2-point clustering information independently of the linear bias and linear redshift-space distortions of the specific galaxy tracers. In this paper, we discuss how to extend the application of ηg,R to quasi-linear scales and how to control and remove observational selection effects, which are typical of redshift surveys as VIPERS, in detail. We verify the accuracy and efficiency of these procedures using mock catalogues that match the survey selection process. These results show the robustness of ηg,R to non-linearities and observational effects, which is related to its very definition as a ratio of quantities that are similarly affected. At an effective redshift z = 0.93, we measured the value ηg,R(15) = 0.141 ± 0.013 at R = 5h-1 Mpc. Within a flat ΛCDM cosmology and by including the best available priors on H0, ns and baryon density, we obtain a matter density parameter at the current epoch Ωm,0 = 0.270-0.025+0.029. In addition to the great precision achieved on our estimation of Ωm using VIPERS PDR-1, this result is remarkable because it appears to be in good agreement with a recent estimate at z ≃ 0.3, which was obtained by applying the same technique to the SDSS-LRG catalogue. It, therefore, supports the robustness of the present analysis. Moreover, the combination of these two measurements at z ~ 0.3 and z ~ 0.9 provides us with a very precise estimate of Ωm,0 = 0.274 ± 0.017, which highlights the great consistency between our estimation and other cosmological probes, such as baryonic acoustic oscillations, cosmic microwave background, and supernovae.
We explore the evolution of the colour–magnitude relation (CMR) and luminosity function (LF) at 0.4 < z < 1.3 from the VIMOS Public Extragalactic Redshift Survey (VIPERS) using ~45 000 galaxies with ...precise spectroscopic redshifts down to \hbox{$i'_{AB} < 22.5$} i AB ′ < 22.5 over ~10.32 deg2 in two fields. From z = 0.5 to z = 1.3 the LF and CMR are well defined for different galaxy populations and \hbox{$M^{*}_{B}$} M B ∗ evolves by ~1.04(1.09) ± 0.06(0.10) mag for the total (red) galaxy sample. We compare different criteria for selecting early-type galaxies: (1) a fixed cut in rest-frame (U − V) colours, (2) an evolving cut in (U − V) colours, (3) a rest-frame (NUV − r′) − (r′ − K) colour selection, and (4) a spectral-energy-distribution classification. The completeness and contamination varies for the different methods and with redshift, but regardless of the method we measure a consistent evolution of the red-sequence (RS). Between 0.4 < z < 1.3 we find a moderate evolution of the RS intercept of Δ(U − V) = 0.28 ± 0.14 mag, favouring exponentially declining star formation (SF) histories with SF truncation at 1.7 ≤ z ≤ 2.3. Together with the rise in the number density of red galaxies by 0.64 dex since z = 1, this suggests a rapid build-up of massive galaxies (M⋆ > 1011 M⊙) 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 early-type galaxies at 0.9 < z < 1.0, in contrast with the quiescent red stellar populations of early-type galaxies at 0.5 < z < 0.6. There is an increase in the observed CMR scatter with redshift, which is two times larger than observed in galaxy clusters and at variance with theoretical model predictions. 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.
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