Showing papers by "A. Iovino published in 2016"
DSM1, University of Bonn2, Centre national de la recherche scientifique3, University of Nice Sophia Antipolis4, Istanbul University5, University of Zagreb6, University of Bristol7, University of Bologna8, University of Western Australia9, Max Planck Society10, Paris Diderot University11, University of Geneva12, European Southern Observatory13, University of Birmingham14, Ludwig Maximilian University of Munich15, University of Oxford16, University of Paris17, University of Michigan18, Aryabhatta Research Institute of Observational Sciences19, University of Liège20, Durham University21, University of KwaZulu-Natal22, Université Paris-Saclay23, Chalmers University of Technology24, INAF25, University of Victoria26, Liverpool John Moores University27, Australian Astronomical Observatory28, University of Chicago29, Taras Shevchenko National University of Kyiv30, University of Illinois at Urbana–Champaign31, Aristotle University of Thessaloniki32, National Institute of Astrophysics, Optics and Electronics33, University of Copenhagen34, Presidency University, Kolkata35, Leiden University36, Stanford University37, Goddard Space Flight Center38, Princeton University39, University of California, Davis40
TL;DR: The XXL-XMM survey as discussed by the authors provides constraints on the dark energy equation of state from the space-time distribution of clusters of galaxies and serves as a pathfinder for future, wide-area X-ray missions.
Abstract: Context. The quest for the cosmological parameters that describe our universe continues to motivate the scientific community to undertake very large survey initiatives across the electromagnetic spectrum. Over the past two decades, the Chandra and XMM-Newton observatories have supported numerous studies of X-ray-selected clusters of galaxies, active galactic nuclei (AGNs), and the X-ray background. The present paper is the first in a series reporting results of the XXL-XMM survey; it comes at a time when the Planck mission results are being finalised. Aims. We present the XXL Survey, the largest XMM programme totaling some 6.9 Ms to date and involving an international consortium of roughly 100 members. The XXL Survey covers two extragalactic areas of 25 deg(2) each at a point-source sensitivity of similar to 5 x 10(-15) erg s(-1) cm(-2) in the [0.5-2] keV band (completeness limit). The survey's main goals are to provide constraints on the dark energy equation of state from the space-time distribution of clusters of galaxies and to serve as a pathfinder for future, wide-area X-ray missions. We review science objectives, including cluster studies, AGN evolution, and large-scale structure, that are being conducted with the support of approximately 30 follow-up programmes. Methods. We describe the 542 XMM observations along with the associated multi-lambda and numerical simulation programmes. We give a detailed account of the X-ray processing steps and describe innovative tools being developed for the cosmological analysis. Results. The paper provides a thorough evaluation of the X-ray data, including quality controls, photon statistics, exposure and background maps, and sky coverage. Source catalogue construction and multi-lambda associations are briefly described. This material will be the basis for the calculation of the cluster and AGN selection functions, critical elements of the cosmological and science analyses. Conclusions. The XXL multi-lambda data set will have a unique lasting legacy value for cosmological and extragalactic studies and will serve as a calibration resource for future dark energy studies with clusters and other X-ray selected sources. With the present article, we release the XMM XXL photon and smoothed images along with the corresponding exposure maps.
272 citations
University of Bonn1, Max Planck Society2, University of Bristol3, Centre national de la recherche scientifique4, DSM5, University of Birmingham6, University of Nice Sophia Antipolis7, Istanbul University8, University of Florida9, Liverpool John Moores University10, INAF11, University of Geneva12, University of Michigan13, University of KwaZulu-Natal14, Chalmers University of Technology15, Brera Astronomical Observatory16, Australian Astronomical Observatory17, European Southern Observatory18, University of Illinois at Urbana–Champaign19, Macquarie University20, University of Copenhagen21, Ludwig Maximilian University of Munich22, University of Victoria23
TL;DR: In this paper, the authors presented the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of 3 x 10−1−4 erg s−1) cm−2 on the source flux within a 1' aperture.
Abstract: Context. The XXL Survey is the largest survey carried out by the XMM-Newton satellite and covers a total area of 50 square degrees distributed over two fields. It primarily aims at investigating the large-scale structures of the Universe using the distribution of galaxy clusters and active galactic nuclei as tracers of the matter distribution. The survey will ultimately uncover several hundreds of galaxy clusters out to a redshift of similar to 2 at a sensitivity of similar to 10 (14) erg s (1) cm (2) in the [0.5-2] keV band. Aims. This article presents the XXL bright cluster sample, a subsample of 100 galaxy clusters selected from the full XXL catalogue by setting a lower limit of 3 x 10(-1)4 erg s(-1) cm(-2) on the source flux within a 1' aperture. Methods. The selection function was estimated using a mixture of Monte Carlo simulations and analytical recipes that closely reproduce the source selection process. An extensive spectroscopic follow-up provided redshifts for 97 of the 100 clusters. We derived accurate X-ray parameters for all the sources. Scaling relations were self-consistently derived from the same sample in other publications of the series. On this basis, we study the number density, luminosity function, and spatial distribution of the sample. Results. The bright cluster sample consists of systems with masses between M-500 = 7 x 10(13) and 3 x 10(14) M-circle dot, mostly located between z = 0.1 and 0.5. The observed sky density of clusters is slightly below the predictions from the WMAP9 model, and significantly below the prediction from the Planck 2015 cosmology. In general, within the current uncertainties of the cluster mass calibration, models with higher values of sigma(8) and/or Omega(M) appear more difficult to accommodate. We provide tight constraints on the cluster differential luminosity function and find no hint of evolution out to z similar to 1. We also find strong evidence for the presence of large-scale structures in the XXL bright cluster sample and identify five new superclusters.
135 citations
TL;DR: In this paper, the authors present measurements of the growth rate of cosmological structure from the modelling of the anisotropic galaxy clustering measured in the final data release of the VIPERS survey.
Abstract: We present measurements of the growth rate of cosmological structure from the modelling of the anisotropic galaxy clustering measured in the final data release of the VIPERS survey. The analysis is carried out in configuration space and based on measurements of the first two even multipole moments of the anisotropic galaxy auto-correlation function, in two redshift bins spanning the range $0.5 < z < 1.2$. We provide robust and cosmology-independent corrections for the VIPERS angular selection function, allowing recovery of the underlying clustering amplitude at the percent level down to the Mpc scale. We discuss several improvements on the non-linear modelling of redshift-space distortions (RSD) and perform detailed tests of a variety of approaches against a set of realistic VIPERS-like mock realisations. This includes using novel fitting functions to describe the velocity divergence and density power spectra $P_{\theta\theta}$ and $P_{\delta\theta}$ that appear in RSD models. These tests show that we are able to measure the growth rate with negligible bias down to separations of $5h^{-1}Mpc$. Interestingly, the application to real data shows a weaker sensitivity to the details of non-linear RSD corrections compared to mock results. We obtain consistent values for the growth rate times the matter power spectrum normalisation parameter of $f\sigma_8=0.55\pm 0.12$ and $0.40\pm0.11$ at effective redshifts of $z = 0.6$ and $z=0.86$ respectively. These results are in agreement with standard cosmology predictions assuming Einstein gravity in a $\Lambda \rm{CDM}$ background.
133 citations
INAF1, Aix-Marseille University2, University of Bologna3, University of Milan4, University of the South, Toulon-Var5, Roma Tre University6, University of Nice Sophia Antipolis7, University of Geneva8, University of Paris-Sud9, Jan Kochanowski University10, Pierre-and-Marie-Curie University11, Jagiellonian University12, University of Portsmouth13
TL;DR: In this article, the authors exploit the first public data release of VIPERS to investigate environmental effects in the evolution of galaxies between z similar to 0.5 and 0.9, and find that the galaxy stellar mass function in the densest regions has a different shape than was measured at low densities.
Abstract: We exploit the first public data release of VIPERS to investigate environmental effects in the evolution of galaxies between z similar to 0.5 and 0.9. The large number of spectroscopic redshifts (more than 50 000) over an area of about 10 deg(2) provides a galaxy sample with high statistical power. The accurate redshift measurements (sigma(z) = 0.00047(1+ z(spec))) allow us to robustly isolate galaxies living in the lowest and highest density environments (delta \textless 0.7 and delta \textgreater 4, respectively) as defined in terms of spatial 3D density contrast delta. We estimate the stellar mass function of galaxies residing in these two environments and constrain the high-mass end (M greater than or similar to 10(11) M-circle dot) 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 \textless 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.
78 citations
University of Geneva1, University of Bonn2, Lund University3, National Institute of Astrophysics, Optics and Electronics4, Aristotle University of Thessaloniki5, Aix-Marseille University6, INAF7, University of Bologna8, Ludwig Maximilian University of Munich9, National Academy of Sciences of Ukraine10, Australian Astronomical Observatory11, University of Zagreb12, Istanbul University13, University of Florida14, Liverpool John Moores University15, University of Bristol16, University of KwaZulu-Natal17, Chalmers University of Technology18, University of Hamburg19, University of Nice Sophia Antipolis20, University of Illinois at Urbana–Champaign21, Max Planck Society22, European Southern Observatory23, University of California, Davis24, University of Victoria25
TL;DR: In this paper, the authors presented the first release of the XXL-1000-AGN point source catalogue including four optical photometry bands and redshift estimates in the 2-10 keV energy band with the goal of providing a sizable sample useful for AGN studies.
Abstract: Context. X-ray extragalactic surveys are ideal laboratories for the study of the evolution and clustering of active galactic nuclei (AGN). Usually, a combination of deep and wide surveys is necessary to create a complete picture of the population. Deep X-ray surveys provide the faint population at high redshift, while wide surveys provide the rare bright sources. Nevertheless, very wide area surveys often lack the ancillary information available for modern deep surveys. The XXL survey spans two fields of a combined 50 deg(2) observed for more than 6Ms with XMM-Newton, occupying the parameter space that lies between deep surveys and very wide area surveys; at the same time it benefits from a wealth of ancillary data. Aims. This paper marks the first release of the XXL point source catalogue including four optical photometry bands and redshift estimates. Our sample is selected in the 2-10 keV energy band with the goal of providing a sizable sample useful for AGN studies. The limiting flux is F2-10 keV = 4.8 x 10(14) erg s(-1) cm(-2). Methods. We use both public and proprietary data sets to identify the counterparts of the X-ray point-like sources by means of a likelihood ratio test. We improve upon the photometric redshift determination for AGN by applying a Random Forest classification trained to identify for each object the optimal photometric redshift category (passive, star forming, starburst, AGN, quasi-stellar objects (QSO)). Additionally, we assign a probability to each source that indicates whether it might be a star or an outlier. We apply Bayesian analysis to model the X-ray spectra assuming a power-law model with the presence of an absorbing medium. Results. We find that the average unabsorbed photon index is \textlessGamma \textgreater = 1.85 +/- 0.40 while the average hydrogen column density is log \textless N-H \textgreater i = 21.07 +/- 1.2 cm(-2). We find no trend of Gamma or N-H with redshift and a fraction of 26% absorbed sources (log N-H \textgreater 22) consistent with the literature on bright sources (log L-x \textgreater 44). The counterpart identification rate reaches 96.7% for sources in the northern field, 97.7% for the southern field, and 97.2% in total. The photometric redshift accuracy is 0.095 for the full XMM-XXL with 28% catastrophic outliers estimated on a sample of 339 sources. Conclusions. We show that the XXL-1000-AGN sample number counts extended the number counts of the COSMOS survey to higher fluxes and are fully consistent with the Euclidean expectation. We constrain the intrinsic luminosity function of AGN in the 2-10 keV energy band where the unabsorbed X-ray flux is estimated from the X-ray spectral fit up to z = 3. Finally, we demonstrate the presence of a supercluster size structure at redshift 0.14, identified by means of percolation analysis of the XXL-1000-AGN sample. The XXL survey, reaching a medium flux limit and covering a wide area, is a stepping stone between current deep fields and planned wide area surveys.
55 citations
TL;DR: In this article, the authors trace the evolution and the star formation history of passive galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS).
Abstract: We trace the evolution and the star formation history of passive galaxies, using a subset of the VIMOS Public Extragalactic Redshift Survey (VIPERS). We extracted from the VIPERS survey a sample of passive galaxies in the redshift range 0.4
45 citations
INAF1, University of Milan2, Aix-Marseille University3, University of Nice Sophia Antipolis4, University of Geneva5, University of Bologna6, Jan Kochanowski University7, University of Toulouse8, Jagiellonian University9, Roma Tre University10, Pierre-and-Marie-Curie University11, University of Saint Mary12, University of Edinburgh13, Institut Universitaire de France14
TL;DR: In this paper, the authors present the full public data release (PDR-2) of the VIMOS Public Extragalactic Redshift Survey (VIPERS), performed at the ESO VLT.
Abstract: We present the full public data release (PDR-2) of the VIMOS Public Extragalactic Redshift Survey (VIPERS), performed at the ESO VLT. We release redshifts, spectra, CFHTLS magnitudes and ancillary information (as masks and weights) for a complete sample of 86,775 galaxies (plus 4,732 other objects, including stars and serendipitous galaxies); we also include their full photometrically-selected parent catalogue. The sample is magnitude limited to i_AB = 2 are shown to have a confidence level of 96% or larger and make up 88% of all measured galaxy redshifts (76,552 out of 86,775), constituting the VIPERS prime catalogue for statistical investigations. For this sample the rms redshift error, estimated using repeated measurements of about 3,000 galaxies, is found to be sigma_z = 0.00054(1+z). All data are available at this http URL and on the ESO Archive.
45 citations
TL;DR: In this paper, the authors explore the evolution of the statistical distribution of galaxy morphological properties and colours over the redshift range, combining high-quality imaging data from the CFHT Legacy Survey with the large number of redshifts and extended photometry from the VIPERS survey.
Abstract: We explore the evolution of the statistical distribution of galaxy morphological properties and colours over the redshift range $0.5
43 citations
TL;DR: In this article, the authors measured the cross-correlation between the centres of voids and the complete galaxy catalogue and proposed a linear Gaussian streaming model for the redshift space distortions.
Abstract: We identified voids in the completed VIMOS Public Extragalactic Redshift Survey (VIPERS), using an algorithm based on searching for empty spheres. We measured the cross-correlation between the centres of voids and the complete galaxy catalogue. The cross-correlation function exhibits a clear anisotropy in both VIPERS fields (W1 and W4), which is characteristic of linear redshift space distortions. By measuring the projected cross-correlation and then deprojecting it we are able to estimate the undistorted cross-correlation function. We propose that given a sufficiently well measured cross-correlation function one should be able to measure the linear growth rate of structure by applying a simple linear Gaussian streaming model for the redshift space distortions (RSD). Our study of voids in 306 mock galaxy catalogues mimicking the VIPERS fields would suggest that VIPERS is capable of measuring $\beta$ with an error of around $25\%$. Applying our method to the VIPERS data, we find a value for the redshift space distortion parameter, $\beta = 0.423^{+0.104}_{-0.108}$, which given the bias of the galaxy population we use gives a linear growth rate of $f\sigma_8 = 0.296^{+0.075}_{-0.078}$ at $z = 0.727$. These results are consistent with values observed in parallel VIPERS analysis using standard techniques.
37 citations
TL;DR: In this article, the accuracy of the clustering-based redshift estimation proposed by Menard et al. when applied to VIMOS Public Extragalactic Redshift Survey (VIPERS) and Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) real data is explored.
Abstract: We explore the accuracy of the clustering-based redshift estimation proposed by Menard et al. when applied to VIMOS Public Extragalactic Redshift Survey (VIPERS) and Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) real data. This method enables us to reconstruct redshift distributions from measurement of the angular clustering of objects using a set of secure spectroscopic redshifts. We use state-of-the-art spectroscopic measurements with i(AB) \textless 22.5 from the VIPERS as reference population to infer the redshift distribution of galaxies from the CFHTLS T0007 release. VIPERS provides a nearly representative sample to a flux limit of iAB \textless 22.5 at a redshift of \textgreater 0.5 which allows us to test the accuracy of the clustering-based redshift distributions. We show that this method enables us to reproduce the true mean colour-redshift relation when both populations have the same magnitude limit. We also show that this technique allows the inference of redshift distributions for a population fainter than the reference and we give an estimate of the colour-redshift mapping in this case. This last point is of great interest for future large-redshift surveys which require a complete faint spectroscopic sample.
34 citations
TL;DR: In this paper, a large filamentary structure at z similar to 0.73 in the field of the COSMOS survey, the so-called cosmOS wall, is studied.
Abstract: Aims. We present a study of a large filamentary structure at z similar to 0.73 in the field of the COSMOS survey, the so-called COSMOS Wall. This structure encompasses a comprehensive range of environments from a dense cluster and a number of galaxy groups to filaments, less dense regions, and adjacent voids. It thus provides a valuable laboratory for the accurate mapping of environmental effects on galaxy evolution at a look-back time of similar to 6.5 Gyr, when the Universe was roughly half its present age. Methods. We performed deep spectroscopic observations with VIMOS at VLT of a K-band selected sample of galaxies in this complex structure, building a sample of galaxies complete in galaxy stellar mass down to a lower limit of log(M-*/M-circle dot)similar to 9.8, which is significantly deeper than previously available data. Thanks to its location within the COSMOS survey, each galaxy benefits from a wealth of ancillary information: HST-ACS data with I-band exposures down to I-AB similar to 28 complemented by extensive multiwavelength ground-and space-based observations spanning the entire electromagnetic spectrum. Results. In this paper we detail the survey strategy and weighting scheme adopted to account for the biases introduced by the photometric preselection of our targets. We present our galaxy stellar mass and rest-frame magnitudes estimates together with a group catalog obtained with our new data and their member galaxies color / mass distribution. Conclusions. Owing to our new sample we can perform a detailed, high definition mapping of the complex COSMOS Wall structure. The sharp environmental information, coupled with high quality spectroscopic information and rich ancillary data available in the COSMOS field, enables a detailed study of galaxy properties as a function of local environment in a redshift slice where environmental effects are important, and in a stellar mass range where mass and environment driven effects are both at work.
TL;DR: In this article, a large filamentary structure at z −0.73 in the field of the COSMOS survey is studied, the so-called cosmOS Wall.
Abstract: We present a study of a large filamentary structure at z~0.73 in the field of the COSMOS survey, the so-called COSMOS Wall. This structure encompasses a comprehensive range of environments from a dense cluster and a number of galaxy groups to filaments, less dense regions, and adjacent voids. It thus provides a valuable laboratory for the accurate mapping of environmental effects on galaxy evolution at a look-back time of ~6.5 Gyr, when the Universe was roughly half its present age.
We performed deep spectroscopic observations with VIMOS at VLT of a K-band selected sample of galaxies in this complex structure, building a sample of galaxies complete in galaxy stellar mass down to a lower limit of log(M/M_sun)~ 9.8, which is significantly deeper than previously available data. Thanks to its location within the COSMOS survey, each galaxy benefits from a wealth of ancillary information.
In this paper we detail the survey strategy and weighting scheme adopted to account for the biases introduced by the photometric pre-selection of our targets. We present our galaxy stellar mass and rest-frame magnitudes estimates together with a group catalog obtained with our new data and their member galaxies color/mass distribution.
Owing to to our new sample we can perform a detailed, high definition mapping of the complex COSMOS Wall structure. The sharp environmental information, coupled with high quality spectroscopic information and rich ancillary data available in the COSMOS field, enables a detailed study of galaxy properties as a function of local environment in a redshift slice where environmental effects are important, and in a stellar mass range where mass and environment driven effects are both at work.
University of Geneva1, University of Bonn2, Lund University3, Aristotle University of Thessaloniki4, National Institute of Astrophysics, Optics and Electronics5, Aix-Marseille University6, INAF7, University of Bologna8, Ludwig Maximilian University of Munich9, National Academy of Sciences of Ukraine10, Australian Astronomical Observatory11, University of Zagreb12, Istanbul University13, University of Florida14, Liverpool John Moores University15, University of Bristol16, University of KwaZulu-Natal17, Chalmers University of Technology18, University of Hamburg19, University of Nice Sophia Antipolis20, University of Illinois at Urbana–Champaign21, Max Planck Society22, European Southern Observatory23, University of California, Davis24, University of Victoria25
TL;DR: In this paper, the authors presented the first release of the XXL point source catalogue in the 2-10 keV energy band with limiting flux $F 2 -10keV = 4.8\cdot10^{-14}\rm{erg\,s^{-1}\,cm^{-2}
Abstract: X-ray extragalactic surveys are ideal laboratories for the study of the evolution and clustering of active galactic nuclei (AGN). The XXL Survey spans two fields of a combined 50 $deg^2$ observed for more than 6Ms with XMM-Newton, occupying the parameter space between deep surveys and very wide area surveys; at the same time it benefits from a wealth of ancillary data. This paper marks the first release of the XXL point source catalogue selected in the 2-10 keV energy band with limiting flux $F_{2-10keV}=4.8\cdot10^{-14}\rm{erg\,s^{-1}\,cm^{-2}}$. We use both public and proprietary data sets to identify the counterparts of the X-ray point-like sources and improved upon the photometric redshift determination for AGN by applying a Random Forest classification trained to identify for each object the optimal photometric redshift model library. We also assign a probability to each source to be a star or an outlier. We model with Bayesian analysis the X-ray spectra assuming a power-law model with the presence of an absorbing medium. We find an average unabsorbed photon index of $\Gamma=1.85$ and average hydrogen column density $\log{N_{H}}=21.07 cm^{-2}$. We find no trend of $\Gamma$ or $N_H$ with redshift and a fraction of 26% absorbed sources ($\log N_{H}>22$). We show that the XXL-1000-AGN number counts extended the number counts of the COSMOS survey to higher fluxes and are fully consistent with the Euclidean expectation. We constrain the intrinsic luminosity function of AGN in the 2-10 keV energy band where the unabsorbed X-ray flux is estimated from the X-ray spectral fit up to z=3. Finally, we demonstrate the presence of a supercluster size structure at redshift 0.14, identified by means of percolation analysis of the XXL-1000-AGN sample. The XXL survey, reaching a medium flux limit and covering a wide area is a stepping stone between current deep fields and planned wide area surveys.
TL;DR: In this paper, a wavelet-based method was applied to CFHT Megacam and WIRCAM images to detect significant quantities of diffuse light and are able to constrain their spectral energy distributions.
Abstract: Aims. Within a cluster, gravitational effects can lead to the removal of stars from their parent galaxies and their subsequent dispersal into the intracluster medium. Gas hydrodynamical effects can additionally strip gas and dust from galaxies; both gas and stars contribute to intracluster light (ICL). The properties of the ICL can therefore help constrain the physical processes at work in clusters by serving as a fossil record of the interaction history. Methods. The present study is designed to characterise this ICL for the first time in a similar to 10(14) M-circle dot and z similar to 0.53 cluster of galaxies from imaging and spectroscopic points of view. By applying a wavelet-based method to CFHT Megacam and WIRCAM images, we detect significant quantities of diffuse light and are able to constrain their spectral energy distributions. These sources were then spectroscopically characterised with ESO Multi Unit Spectroscopic Explorer (MUSE) spectroscopic data. MUSE data were also used to compute redshifts of 24 cluster galaxies and search for cluster substructures. Results. An atypically large amount of ICL, equivalent in i' to the emission from two brightest cluster galaxies, has been detected in this cluster. Part of the detected diffuse light has a very weak optical stellar component and apparently consists mainly of gas emission, while other diffuse light sources are clearly dominated by old stars. Furthermore, emission lines were detected in several places of diffuse light. Our spectral analysis shows that this emission likely originates from low-excitation parameter gas. Globally, the stellar contribution to the ICL is about 2.3 x 10(9) yr old even though the ICL is not currently forming a large number of stars. On the other hand, the contribution of the gas emission to the ICL in the optical is much greater than the stellar contribution in some regions, but the gas density is likely too low to form stars. These observations favour ram pressure stripping, turbulent viscous stripping, or supernovae winds as the origin of the large amount of intracluster light. Since the cluster appears not to be in a major merging phase, we conclude that ram pressure stripping is the most plausible process that generates the observed ICL sources. Conclusions. This is one of the first times that we are able to spectroscopically study diffuse light in such a distant and massive cluster, and it demonstrates the potential of MUSE observations for such studies.
TL;DR: In this paper, the authors used the final data from the VIPERS redshift survey to extract an unparalleled sample of more than 2000 massive M > 10^11 M-sun passive galaxies (MPGs) at redshift 0.5 2000 M_sun pc^-2.
Abstract: We use the final data from the VIPERS redshift survey to extract an unparalleled sample of more than 2000 massive M > 10^11 M_sun passive galaxies (MPGs) at redshift 0.5 2000 M_sun pc^-2) MPGs show a constant comoving number density over this redshift range, whilst this increases by a factor ~ 4 for the least dense objects, defined as having Sigma 10^11 M_sun objects). Such systems observed at z ~ 1 in VIPERS, therefore, represent the most plausible progenitors of the subsequent emerging class of larger MPGs.
TL;DR: In this article, a wavelet-based method was used to detect diffuse light in a ~10^14 M_odot and z~0.53 cluster of galaxies from imaging and spectroscopic points of view.
Abstract: Within a cluster, gravitational effects can lead to the removal of stars from their parent galaxies. Gas hydrodynamical effects can additionally strip gas and dust from galaxies. The properties of the ICL can therefore help constrain the physical processes at work in clusters by serving as a fossil record of the interaction history. The present study is designed to characterise this ICL in a ~10^14 M_odot and z~0.53 cluster of galaxies from imaging and spectroscopic points of view. By applying a wavelet-based method to CFHT Megacam and WIRCAM images, we detect significant quantities of diffuse light. These sources were then spectroscopically characterised with MUSE. MUSE data were also used to compute redshifts of 24 cluster galaxies and search for cluster substructures. An atypically large amount of ICL has been detected in this cluster. Part of the detected diffuse light has a very weak optical stellar component and apparently consists mainly of gas emission, while other diffuse light sources are clearly dominated by old stars. Furthermore, emission lines were detected in several places of diffuse light. Our spectral analysis shows that this emission likely originates from low-excitation parameter gas. The stellar contribution to the ICL is about 2.3x10^9 yrs old even though the ICL is not currently forming a large number of stars. On the other hand, the contribution of the gas emission to the ICL in the optical is much greater than the stellar contribution in some regions, but the gas density is likely too low to form stars. These observations favour ram pressure stripping, turbulent viscous stripping, or supernovae winds as the origin of the large amount of intracluster light. Since the cluster appears not to be in a major merging phase, we conclude that ram pressure stripping is the most plausible process that generates the observed ICL sources.
Aix-Marseille University1, University of the South, Toulon-Var2, INAF3, Roma Tre University4, University of Bologna5, Institut Universitaire de France6, University of Milan7, University of Nice Sophia Antipolis8, University of Geneva9, Jan Kochanowski University10, Pierre-and-Marie-Curie University11, Jagiellonian University12, Max Planck Society13, University of Portsmouth14, University of Edinburgh15
TL;DR: In this article, the authors compare three methods to measure the count-in-cell probability density function of galaxies in a spectroscopic redshift survey and find that, when the sampling is low (the average number of objects per cell is around unity), it is necessary to use a parametric method to model the galaxy distribution.
Abstract: We compare three methods to measure the count-in-cell probability density function of galaxies in a spectroscopic redshift survey. From this comparison we found that, when the sampling is low (the average number of object per cell is around unity), it is necessary to use a parametric method to model the galaxy distribution. We used a set of mock catalogues of VIPERS to verify if we were able to reconstruct the cell-count probability distribution once the observational strategy is applied. We find that, in the simulated catalogues, the probability distribution of galaxies is better represented by a Gamma expansion than a skewed log-normal distribution. Finally, we correct the cell-count probability distribution function from the angular selection effect of the VIMOS instrument and study the redshift and absolute magnitude dependency of the underlying galaxy density function in VIPERS from redshift 0.5 to 1.1. We found a very weak evolution of the probability density distribution function and that it is well approximated by a Gamma distribution, independently of the chosen tracers.
INAF1, Roma Tre University2, University of Bologna3, Aix-Marseille University4, University of Milan5, University of Provence6, University of Nice Sophia Antipolis7, Academia Sinica8, Jan Kochanowski University9, Nagoya University10, Institut d'Astrophysique de Paris11, Jagiellonian University12, University of California, Berkeley13, University of Edinburgh14, Istituto Nazionale di Fisica Nucleare15
TL;DR: In this article, the authors used the first release of the VImos Public Extragalactic Redshift Survey of galaxies (VIPERS) of ~50 000 objects to measure the bias relation between galaxies and mass in the redshift range z = [ 0.5, 1.1 ].
Abstract: Aims. We use the first release of the VImos Public Extragalactic Redshift Survey of galaxies (VIPERS) of ~50 000 objects to measure the biasing relation between galaxies and mass in the redshift range z = [ 0.5,1.1 ].Methods. We estimate the 1-point distribution function [PDF] of VIPERS galaxies from counts in cells and, assuming a model for the mass PDF, we infer their mean bias relation. The reconstruction of the bias relation is performed through a novel method that accounts for Poisson noise, redshift distortions, inhomogeneous sky coverage. and other selection effects. With this procedure we constrain galaxy bias and its deviations from linearity down to scales as small as 4 h -1 Mpc and out to z = 1.1. Results. We detect small (up to 2%) but statistically significant (up to 3σ ) deviations from linear bias. The mean biasing function is close to linear in regions above the mean density. The mean slope of the biasing relation is a proxy to the linear bias parameter. This slope increases with luminosity, which is in agreement with results of previous analyses. We detect a strong bias evolution only for z > 0.9, which is in agreement with some, but not all, previous studies. We also detect a significant increase of the bias with the scale, from 4 to 8 h -1 Mpc , now seen for the first time out to z = 1. The amplitude of non-linearity depends on redshift, luminosity, and scale, but no clear trend is detected. Owing to the large cosmic volume probed by VIPERS, we find that the mismatch between the previous estimates of bias at z ~ 1 from zCOSMOS and VVDS-Deep galaxy samples is fully accounted for by cosmic variance. Conclusions. The results of our work confirm the importance of going beyond the over-simplistic linear bias hypothesis showing that non-linearities can be accurately measured through the applications of the appropriate statistical tools to existing datasets like VIPERS.
University of Bologna1, INAF2, Roma Tre University3, University of Nice Sophia Antipolis4, Aix-Marseille University5, University of Milan6, University of the South, Toulon-Var7, University of Geneva8, Jan Kochanowski University9, Pierre-and-Marie-Curie University10, Jagiellonian University11, University of Portsmouth12
TL;DR: In this article, the authors analyzed the first data release of the VIMOS Public Extragalactic Redshift Survey (VIPERS), determining the dependence of the three-point correlation function on luminosity and stellar mass at $z=[0.5, 1.1]$.
Abstract: The three-point correlation function (3PCF) is a powerful probe to investigate the clustering of matter in the Universe in a complementary way with respect to lower-order statistics, providing additional information with respect to the two-point correlation function and allowing us to shed light on biasing, nonlinear processes, and deviations from Gaussian statistics. In this paper, we analyse the first data release of the VIMOS Public Extragalactic Redshift Survey (VIPERS), determining the dependence of the three-point correlation function on luminosity and stellar mass at $z=[0.5,1.1]$. We exploit the VIPERS Public Data Release 1, consisting of more than 50,000 galaxies with B-band magnitudes in the range $-21.6\lesssim M_{\rm B}-5\log(h)\lesssim-19.9$ and stellar masses in the range $9.8\lesssim\log(M_\star[h^{-2}\,M_\odot])\lesssim 10.7$. We measure both the connected 3PCF and the reduced 3PCF in redshift space, probing different configurations and scales, in the range $2.5
INAF1, University of Bologna2, Aix-Marseille University3, University of Milan4, Roma Tre University5, University of Nice Sophia Antipolis6, Jan Kochanowski University7, University of Saint Mary8, Hoffmann-La Roche9, Jagiellonian University10, University of St Andrews11, École normale supérieure de Lyon12, University of Geneva13, University of Edinburgh14
TL;DR: In this article, the authors used the final data of the VIMOS Public Extragalactic Redshift Survey (VIPERS) to investigate the effect of environment on the evolution of galaxies between 0.5 and 0.9.
Abstract: [Abridged] We use the final data of the VIMOS Public Extragalactic Redshift Survey (VIPERS) to investigate the effect of environment on the evolution of galaxies between $z=0.5$ and $z=0.9$. We characterise local environment in terms of the density contrast smoothed over a cylindrical kernel, the scale of which is defined by the distance to the $5^{th}$ nearest neighbour. We find that more massive galaxies tend to reside in higher-density environments over the full redshift range explored. Defining star-forming and passive galaxies through their (NUV$-r$) vs ($r-K$) colours, we then quantify the fraction of star-forming over passive galaxies, $f_{\rm ap}$, as a function of environment at fixed stellar mass. $f_{\rm ap}$ is higher in low-density regions for galaxies with masses ranging from $\log(\mathcal{M}/\mathcal{M}_\odot)=10.38$ (the lowest value explored) to at least $\log(\mathcal{M}/\mathcal{M}_\odot)\sim11.3$, although with decreasing significance going from lower to higher masses. This is the first time that environmental effects on high-mass galaxies are clearly detected at redshifts as high as $z\sim0.9$. We compared these results to VIPERS-like galaxy mock catalogues based on the galaxy formation model of De Lucia & Blaizot. The model correctly reproduces $f_{\rm ap}$ in low-density environments, but underpredicts it at high densities. The discrepancy is particularly strong for the lowest-mass bins. We find that this discrepancy is driven by an excess of low-mass passive satellite galaxies in the model. Looking at the accretion history of these model galaxies, i.e. the times when they become satellites, a better (yet not perfect) agreement with observations can be obtained in high density regions by assuming either that a not-negligible fraction of satellites is destroyed, or that their quenching time-scale is longer than $\sim 2$ Gyr.
Aix-Marseille University1, INAF2, University of Milan3, University of Nice Sophia Antipolis4, University of Bologna5, Jan Kochanowski University6, Hoffmann-La Roche7, Jagiellonian University8, University of St Andrews9, Roma Tre University10, University of Geneva11, University of Saint Mary12, University of Edinburgh13, Spanish National Research Council14, Autonomous University of Madrid15
TL;DR: In this article, a joint analysis of redshift-space distortions and galaxy-galaxy lensing is carried out to measure the growth rate of structure, which is a key quantity for understanding the nature of gravity on cosmological scales.
Abstract: We carry out a joint analysis of redshift-space distortions and galaxy-galaxy lensing, with the aim of measuring the growth rate of structure; this is a key quantity for understanding the nature of gravity on cosmological scales and late-time cosmic acceleration. We make use of the final VIPERS redshift survey dataset, which maps a portion of the Universe at a redshift of $z \simeq 0.8$, and the lensing data from the CFHTLenS survey over the same area of the sky. We build a consistent theoretical model that combines non-linear galaxy biasing and redshift-space distortion models, and confront it with observations. The two probes are combined in a Bayesian maximum likelihood analysis to determine the growth rate of structure at two redshifts $z=0.6$ and $z=0.86$. We obtain measurements of $f\sigma_8(0.6) = 0.48 \pm 0.12$ and $f\sigma_8(0.86) = 0.48 \pm 0.10$. The additional galaxy-galaxylensing constraint alleviates galaxy bias and $\sigma_8$ degeneracies, providing direct measurements of $[f(0.6),\sigma_8(0.6)] = [0.93 \pm 0.22, 0.52 \pm 0.06]$ and $f(0.86),\sigma_8(0.86)] = [0.99 \pm 0.19, 0.48 \pm 0.04]$. These measurements are statistically consistent with a Universe where the gravitational interactions can be described by General Relativity, although they are not yet accurate enough to rule out some commonly considered alternatives. Finally, as a complementary test we measure the gravitational slip parameter, $E_G$ , for the first time at $z>0.6$. We find values of $\smash{\overline{E}_G}(0.6) = 0.16 \pm 0.09$ and $\smash{\overline{E}_G}(0.86) = 0.09 \pm 0.07$, when $E_G$ is averaged over scales above $3 h^{-1} \rm{Mpc}$. We find that our $E_G$ measurements exhibit slightly lower values than expected for standard relativistic gravity in a {\Lambda}CDM background, although the results are consistent within $1-2\sigma$.
TL;DR: In this article, the authors used the final catalogue of the VIMOS Public Extragalactic Redshift Survey (VIPERS) to measure the power spectrum of the galaxy distribution at high redshift, presenting results that extend beyond $z = 1$ for the first time.
Abstract: We use the final catalogue of the VIMOS Public Extragalactic Redshift Survey (VIPERS) to measure the power spectrum of the galaxy distribution at high redshift, presenting results that extend beyond $z=1$ for the first time. We apply an FFT technique to four independent sub-volumes comprising a total of $51,728$ galaxies at $0.6
INAF1, Jan Kochanowski University2, University of Milan3, Aix-Marseille University4, University of Nice Sophia Antipolis5, University of Bologna6, University of Saint Mary7, Hoffmann-La Roche8, Jagiellonian University9, University of St Andrews10, Roma Tre University11, University of Geneva12, University of Edinburgh13
TL;DR: In this paper, the authors use the VIPERS redshift survey in combination with SDSS-DR7 to explore the relationships between star-formation history, stellar mass and galaxy structure, and how these relationships have evolved since z~1.5.
Abstract: We use the full VIPERS redshift survey in combination with SDSS-DR7 to explore the relationships between star-formation history (using d4000), stellar mass and galaxy structure, and how these relationships have evolved since z~1. We trace the extents and evolutions of both the blue cloud and red sequence, by fitting double Gaussians to the d4000 distribution of galaxies in narrow stellar mass bins, for four redshift intervals over 0 10^11 M_sun, d4000<1.55) drops sharply by a factor five between z~0.8 and z~0.5. These galaxies are becoming quiescent at a rate that largely matches the increase in the numbers of massive passive galaxies seen over this period. We examine the size-mass relation of blue cloud galaxies, finding that its high-mass boundary runs along lines of constant M*/r_e or equivalently inferred velocity dispersion. Larger galaxies can continue to form stars to higher stellar masses than smaller galaxies. As blue cloud galaxies approach this high-mass limit, they start to be quenched, their d4000 values increasing to push them towards the green valley. In parallel, their structures change, showing higher Sersic indices and central stellar mass densities. For these galaxies, bulge growth is necessary for them to reach the high-mass limit of the blue cloud and be quenched by internal mechanisms. The blue cloud galaxies that are being quenched at z~0.8 lie along the same size-mass relation as present day quiescent galaxies, and seem the likely progenitors of today's S0s.
TL;DR: The XXL survey currently covers two 25 sq. deg. X-ray (z 1 cluster density) patches with XMM observations of ~10k as discussed by the authors, which will eventually constitute a reference study and an ideal calibration field for the upcoming eROSITA and Euclid missions.
Abstract: The XXL survey currently covers two 25 sq. deg. patches with XMM observations of ~10ks. We summarise the scientific results associated with the first release of the XXL data set, that occurred mid 2016. We review several arguments for increasing the survey depth to 40 ks during the next decade of XMM operations. X-ray (z 1 cluster density. It will eventually constitute a reference study and an ideal calibration field for the upcoming eROSITA and Euclid missions.
TL;DR: An algorithm for identifying and repairing spurious residual features in sky-subtracted galaxy spectra is presented by using data from the VIMOS Public Extragalactic Redshift Survey (VIPERS) as a test case and finds that the automatic technique reproduces the time-consuming manual cleaning in a uniform and objective manner across a large data sample.
Abstract: Identifying spurious reduction artefacts in galaxy spectra is a challenge for large surveys. We present an algorithm for identifying and repairing residual spurious features in sky-subtracted galaxy spectra with application to the VIPERS survey. The algorithm uses principal component analysis (PCA) applied to the galaxy spectra in the observed frame to identify sky line residuals imprinted at characteristic wavelengths. We further model the galaxy spectra in the rest-frame using PCA to estimate the most probable continuum in the corrupted spectral regions, which are then repaired. We apply the method to 90,000 spectra from the VIPERS survey and compare the results with a subset where careful editing was performed by hand. We find that the automatic technique does an extremely good job in reproducing the time-consuming manual cleaning and does it in a uniform and objective manner across a large data sample. The mask data products produced in this work are released together with the VIPERS second public data release (PDR-2).