The cosmological analysis of X-ray cluster surveys: II- Application of the CR-HR method to the XMM archive

We have processed 2774 high-galactic observations from the XMM archive (as of May 2010) and extracted a serendipitous catalogue of some 850 clusters of galaxies based on purely X-ray criteria, following the methodology developed for the XMM-LSS survey. Restricting the sample to the highest signal-to-noise objects (347 clusters), we perform a cosmological analysis using the X-ray information only. The analysis consists in the modelling of the observed colour-magnitude (CR-HR) diagram constructed from cluster instrumental count-rates measured in the [0.5-2], [1-2] and [0.5-1] keV bands. A MCMC procedure simultaneously fits the cosmological parameters, the evolution of the cluster scaling laws and the selection effects. Our results are consistent with the sigma_8 and Omega_m values obtained by WMAP-5 and point toward a negative evolution of the cluster scaling relations with respect to the self-similar expectation. We are further able to constrain the cluster fractional radius xc0=r_c/r500c, to xc0=0.24 +/- 0.04. This study stresses again the critical role of selection effects in deriving cluster scaling relations, even in the local universe. Finally, we show that CR-HR method applied to the eRosita all-sky survey - provided that cluster photometric redshifts are available - will enable the determination of the equation of state of the dark energy at the level of the DETF stage IV predictions; simultaneously, the evolution of the cluster scaling-relations will be unambiguously determined. The XMM CLuster Archive Super Survey (XCLASS) serendipitous cluster catalogue is available online at: http://xmm-lss.in2p3.fr:8080/l4sdb/.Comment: 26 pages, 24 figures, 9 tables. Accepted for publication in MNRAS (minor changes with respect to submitted version). The corresponding galaxy cluster catalogue is available at http://xmm-lss.in2p3.fr:8080/l4sdb

The XMM-LSS Survey: A well controlled X-ray cluster sample over the D1 CFHTLS area

We present the XMM-LSS cluster catalogue corresponding to the CFHTLS D1 area. The list contains 13 spectroscopically confirmed, X-ray selected galaxy clusters over 0.8 deg2 to a redshift of unity and so constitutes the highest density sample of clusters to date. Cluster X-ray bolometric luminosities range from 0.03 to 5x10^{44} erg/s. In this study, we describe our catalogue construction procedure: from the detection of X-ray cluster candidates to the compilation of a spectroscopically confirmed cluster sample with an explicit selection function. The procedure further provides basic X-ray products such as cluster temperature, flux and luminosity. We detected slightly more clusters with a (0.5-2.0 keV) X-ray fluxes of >2x10^{-14} erg/s/cm^{-2} than we expected based on expectations from deep ROSAT surveys. We also present the Luminosity-Temperature relation for our 9 brightest objects possessing a reliable temperature determination. The slope is in good agreement with the local relation, yet compatible with a luminosity enhancement for the 0.15 < z< 0.35 objects having 1 < T < 2 keV, a population that the XMM-LSS is identifying systematically for the first time. The present study permits the compilation of cluster samples from XMM images whose selection biases are understood. This allows, in addition to studies of large-scale structure, the systematic investigation of cluster scaling law evolution, especially for low mass X-ray groups which constitute the bulk of our observed cluster population. All cluster ancillary data (images, profiles, spectra) are made available in electronic form via the XMM-LSS cluster database.Comment: 12 pages 5 figures, MNRAS accepted. The paper with full resolution cluster images is available at http://vela.astro.ulg.ac.be/themes/spatial/xmm/LSS/rel_pub_e.htm

Iterative reconstruction of a global metabolic model of Acinetobacter baylyi ADP1 using high-throughput growth phenotype and gene essentiality data

<p>Abstract</p> <p>Background</p> <p>Genome-scale metabolic models are powerful tools to study global properties of metabolic networks. They provide a way to integrate various types of biological information in a single framework, providing a structured representation of available knowledge on the metabolism of the respective species.</p> <p>Results</p> <p>We reconstructed a constraint-based metabolic model of <it>Acinetobacter baylyi </it>ADP1, a soil bacterium of interest for environmental and biotechnological applications with large-spectrum biodegradation capabilities. Following initial reconstruction from genome annotation and the literature, we iteratively refined the model by comparing its predictions with the results of large-scale experiments: (1) high-throughput growth phenotypes of the wild-type strain on 190 distinct environments, (2) genome-wide gene essentialities from a knockout mutant library, and (3) large-scale growth phenotypes of all mutant strains on 8 minimal media. Out of 1412 predictions, 1262 were initially consistent with our experimental observations. Inconsistencies were systematically examined, leading in 65 cases to model corrections. The predictions of the final version of the model, which included three rounds of refinements, are consistent with the experimental results for (1) 91% of the wild-type growth phenotypes, (2) 94% of the gene essentiality results, and (3) 94% of the mutant growth phenotypes. To facilitate the exploitation of the metabolic model, we provide a web interface allowing online predictions and visualization of results on metabolic maps.</p> <p>Conclusion</p> <p>The iterative reconstruction procedure led to significant model improvements, showing that genome-wide mutant phenotypes on several media can significantly facilitate the transition from genome annotation to a high-quality model.</p

Quantum Confinement and Electronic Structure at the Surface of van der Waals Ferroelectric {\alpha}-In2_{2}Se3_{3}

Two-dimensional (2D) ferroelectric (FE) materials are promising compounds for next-generation nonvolatile memories, due to their low energy consumption and high endurance. Among them, {\alpha}-In$_{2}$Se$_{3}$ has drawn particular attention due to its in- and out-of-plane ferroelectricity, whose robustness has been demonstrated down to the monolayer limit. This is a relatively uncommon behavior since most bulk FE materials lose their ferroelectric character at the 2D limit due to depolarization field. Using angle resolved photoemission spectroscopy (ARPES), we unveil another unusual 2D phenomena appearing in 2H \alpha-In$_{2}$Se$_{3}$ single crystals, the occurrence of a highly metallic two-dimensional electron gas (2DEG) at the surface of vacuum-cleaved crystals. This 2DEG exhibits two confined states which correspond to an electron density of approximatively 10$^{13}$ electrons/cm$^{3}$, also confirmed by thermoelectric measurements. Combination of ARPES and density functional theory (DFT) calculations reveals a direct band gap of energy equal to 1.3 +/- 0.1 eV, with the bottom of the conduction band localized at the center of the Brillouin zone, just below the Fermi level. Such strong n-type doping further supports the quantum confinement of electrons and the formation of the 2DEG.Comment: 20 pages, 12 figure

The SPLASH Survey: Quiescent Galaxies Are More Strongly Clustered but Are Not Necessarily Located in High-density Environments

We use the stellar-mass-selected catalog from the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) in the COSMOS field to study the environments of galaxies via galaxy density and clustering analyses up to z ~ 2.5. The clustering strength of quiescent galaxies exceeds that of star-forming galaxies, implying that quiescent galaxies are preferentially located in more massive halos. When using local density measurement, we find a clear positive quiescent fraction–density relation at z 1.5, the quiescent fraction depends little on the local density, even though clustering shows that quiescent galaxies are in more massive halos. We argue that at high redshift the typical halo size falls below 10^(13)M⊙, where intrinsically the local density measurements are so varied that they do not trace the halo mass. Our results thus suggest that in the high-redshift universe, halo mass may be the key in quenching the star formation in galaxies, rather than the conventionally measured galaxy density

Extragalactic Science, Cosmology and Galactic Archaeology with the Subaru Prime Focus Spectrograph (PFS)

The Subaru Prime Focus Spectrograph (PFS) is a massively-multiplexed fiber-fed optical and near-infrared 3-arm spectrograph (N_fiber=2400, 380<lambda<1260nm, 1.3 degree diameter FoV), offering unique opportunities in survey astronomy. Here we summarize the science case feasible for a survey of Subaru 300 nights. We describe plans to constrain the nature of dark energy via a survey of emission line galaxies spanning a comoving volume of 9.3 (Gpc/h)^3 in the redshift range 0.8<z<2.4. In each of 6 redshift bins, the cosmological distances will be measured to 3% precision via BAO, and redshift-space distortions will be used to constrain structure growth to 6% precision. In the GA program, radial velocities and chemical abundances of stars in the Milky Way and M31 will be used to infer the past assembly histories of spiral galaxies and the structure of their dark matter halos. Data will be secured for 10^6 stars in the Galactic thick-disk, halo and tidal streams as faint as V~22, including stars with V < 20 to complement the goals of the Gaia mission. A medium-resolution mode with R = 5000 to be implemented in the red arm will allow the measurement of multiple alpha-element abundances and more precise velocities for Galactic stars, elucidating the detailed chemo-dynamical structure and evolution of each of the main stellar components of the Milky Way Galaxy and of its dwarf spheroidal galaxies. For the extragalactic program, our simulations suggest the wide avelength range will be powerful in probing the galaxy population and its clustering over a wide redshift range. We propose to conduct a color-selected survey of 1<z<2 galaxies and AGN over 16 deg^2 to J~23.4, yielding a fair sample of galaxies with stellar masses above ~10^{10}Ms at z~2. A two-tiered survey of higher redshift LBGs and LAEs will quantify the properties of early systems close to the reionization epoch.Comment: This document describes the scientific program and requirements for the Subaru Prime Focus Spectrograph (PFS) project. Made significant revision based on studies for the Preliminary Design Review (PRD) held in Feb 2013. The higher-resolution paper file is available from http://member.ipmu.jp/masahiro.takada/pfs_astroph_rv.pd

The XMM-LSS cluster sample and its cosmological applications. Prospects for the XMM next decade

The well defined selection function of the XMM-LSS survey enables a simultaneous modelling of the observed cluster number counts and of the evolution of the L-T relation. We present results pertaining to the first 5 deg2 for a well controlled sample comprising 30 objects: they are compatible with the WMAP3 parameter set along with cluster self-similar evolution. Extending such a survey to 200 deg2 would (1) allow discriminating between the major scenarios of the cluster L-T evolution and (2) provide a unique self-sufficient determination of sigma8 and Gamma with an accuracy of ~ 5% and 10% respectively, when adding mass information from weak lensing and S-Z observations.Comment: Proceedings of the "XMM-Newton: the next decade", to appear in Astronomische Nachrichte

A Telescope Search for Decaying Relic Axions

A search for optical line emission from the two-photon decay of relic axions was conducted in the galaxy clusters Abell 2667 and 2390, using spectra from the VIMOS (Visible Multi-Object Spectrograph) integral field unit at the Very Large Telescope. New upper limits to the two-photon coupling of the axion are derived, and are at least a factor of 3 more stringent than previous upper limits in this mass window. The improvement follows from larger collecting area, integration time, and spatial resolution, as well as from improvements in signal to noise and sky subtraction made possible by strong-lensing mass models of these clusters. The new limits either require that the two-photon coupling of the axion be extremely weak or that the axion mass window between 4.5 eV and 7.7 eV be closed. Implications for sterile-neutrino dark matter are discussed briefly also.Comment: 14 pages, 10 figures, replaced with version published in Phys. Rev.

Unveiling Cosmic Dawn: the synergetic role of space and ground-based telescopes

Large scale structure and cosmolog

The zCOSMOS 10k-Bright Spectroscopic Sample

We present spectroscopic redshifts of a large sample of galaxies with I_(AB) < 22.5 in the COSMOS field, measured from spectra of 10,644 objects that have been obtained in the first two years of observations in the zCOSMOS-bright redshift survey. These include a statistically complete subset of 10,109 objects. The average accuracy of individual redshifts is 110 km s^(–1), independent of redshift. The reliability of individual redshifts is described by a Confidence Class that has been empirically calibrated through repeat spectroscopic observations of over 600 galaxies. There is very good agreement between spectroscopic and photometric redshifts for the most secure Confidence Classes. For the less secure Confidence Classes, there is a good correspondence between the fraction of objects with a consistent photometric redshift and the spectroscopic repeatability, suggesting that the photometric redshifts can be used to indicate which of the less secure spectroscopic redshifts are likely right and which are probably wrong, and to give an indication of the nature of objects for which we failed to determine a redshift. Using this approach, we can construct a spectroscopic sample that is 99% reliable and which is 88% complete in the sample as a whole, and 95% complete in the redshift range 0.5 < z < 0.8. The luminosity and mass completeness levels of the zCOSMOS-bright sample of galaxies is also discussed