Saint-Rémy-de-Provence, France
Saint-Rémy-de-Provence, France

Time filter

Source Type

Bouche N.,Max Planck Institute for Extraterrestrial Physics | Murphy M.T.,Swinburne University of Technology | Peroux C.,Observatoire Astronomique de Marseille Provence
EAS Publications Series | Year: 2012

Low-ionization transitions such as the Mg II λ2796/2803 doublet trace cold gas in the vicinity of galaxies. The exact physical origin of this cold gas traced by QSO absorption lines is debated. Does it trace gas in disks, halos, merger tails, and even in outflows? Recent studies of strong starbursts and post-starbursts at intermediate redshifts have shown that MgII are seen in outflows, with blue-shifted velocities ∼500 - 1500kms-1. Strong intervening MgII absorbers (with equivalent width Wr λ2796 > 1 Å) may be tracing the denser and colder gas of starburst-driven outflows. Indeed, based on MgII statistics, our clustering analysis has shown that the host-galaxy mass is anti-correlated with the line-of-sight velocity Δv (as measured from Wr λ2796). If MgII absorbers were virialized in galaxy halos, a positive Mh-Wr correlation would have been observed. Our result thus shows that the Mg II clouds are not virialized in the gaseous halos of the host-galaxies. © EAS, EDP Sciences 2012.

Laureijs R.,European Space Agency | Gondoin P.,European Space Agency | Duvet L.,European Space Agency | Saavedra Criado G.,European Space Agency | And 17 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Euclid is a space-borne survey mission developed and operated by ESA. It is designed to understand the origin of the Universe's accelerating expansion. Euclid will use cosmological probes to investigate the nature of dark energy, dark matter and gravity by tracking their observational signatures on the geometry of the Universe and on the history of structure formation. The mission is optimised for the measurement of two independent cosmological probes: weak gravitational lensing and galaxy clustering. The payload consists of a 1.2 m Korsch telescope designed to provide a large field of view. The light is directed to two instruments provided by the Euclid Consortium: a visual imager (VIS) and a near-infrared spectrometer-photometer (NISP). Both instruments cover a large common field of view of 0.54 deg2, to be able to survey at least 15,000 deg2 for a nominal mission of 6 years. An overview of the mission will be presented: the scientific objectives, payload, satellite, and science operations. We report on the status of the Euclid mission with a foreseen launch in 2019. © 2012 SPIE.

Pieri M.M.,Ohio State University | Pieri M.M.,University of Colorado at Boulder | Frank S.,Observatoire Astronomique de Marseille Provence | Weinberg D.H.,Ohio State University | And 3 more authors.
Astrophysical Journal Letters | Year: 2010

We present a new method for probing the physical conditions and metal enrichment of the intergalactic medium: the composite spectrum of Lyα forest absorbers. We apply this technique to a sample of 9480 Lyα absorbers with redshift 2 < z < 3.5 identified in the spectra of 13,279 high-redshift quasars from the Sloan Digital Sky Survey (SDSS) Fifth Data Release (DR5). Absorbers are selected as local minima in the spectra with 2.4 < τLyα < 4.0; at SDSS resolution (≈150 km s -1 FWHM), these absorbers are blends of systems that are individually weaker. In the stacked spectra, we detect seven Lyman series lines and metal lines of O VI, N V, C IV, C III, Si IV, C II, Al II, Si II, Fe II, Mg II, and O I. Many of these lines have peak optical depths of <0.02, but they are nonetheless detected at high statistical significance. Modeling the Lyman series measurements implies that our selected systems have total Hi column densities NHI ≈ 1015.4 cm-2. Assuming typical physical conditions ρ/ρ̄= 10, T = 104-104.5 K, and [Fe/H]= -2 yields reasonable agreement with the line strengths of high-ionization species, but it underpredicts the low-ionization species by two orders of magnitude or more. This discrepancy suggests that the low-ionization lines arise in dense, cool, metal-rich clumps, present in some absorption systems. © 2010 The American Astronomical Society. All rights reserved.

Serra P.,NASA | Amblard A.,NASA | Temi P.,NASA | Burgarella D.,Observatoire Astronomique de Marseille Provence | And 4 more authors.
Astrophysical Journal | Year: 2011

We introduce a fast Markov Chain Monte Carlo (MCMC) exploration of the astrophysical parameter space using a modified version of the publicly available code Code Investigating GALaxy Emission (CIGALE). The original CIGALE builds a grid of theoretical spectral energy distribution (SED) models and fits to photometric fluxes from ultraviolet to infrared to put constraints on parameters related to both formation and evolution of galaxies. Such a grid-based method can lead to a long and challenging parameter extraction since the computation time increases exponentially with the number of parameters considered and results can be dependent on the density of sampling points, which must be chosen in advance for each parameter. MCMC methods, on the other hand, scale approximately linearly with the number of parameters, allowing a faster and more accurate exploration of the parameter space by using a smaller number of efficiently chosen samples. We test our MCMC version of the code CIGALE (called CIGALEMC) with simulated data. After checking the ability of the code to retrieve the input parameters used to build the mock sample, we fit theoretical SEDs to real data from the well-known and -studied Spitzer Infrared Nearby Galaxy Survey sample. We discuss constraints on the parameters and show the advantages of our MCMC sampling method in terms of accuracy of the results and optimization of CPU time. © 2011. The American Astronomical Society. All rights reserved.

Tingley B.,Insituto de Astrofisica de Canarias | Tingley B.,University of La Laguna | Bonomo A.S.,Observatoire Astronomique de Marseille Provence | Deeg H.J.,Insituto de Astrofisica de Canarias | Deeg H.J.,University of La Laguna
Astrophysical Journal | Year: 2011

One of the persistent complications in searches for transiting exoplanets is the low percentage of the detected candidates that ultimately prove to be planets, which significantly increases the load on the telescopes used for the follow-up observations to confirm or reject candidates. Several attempts have been made at creating techniques that can pare down candidate lists without the need of additional observations. Some of these techniques involve a detailed analysis of light curve characteristics; others estimate the stellar density or some proxy thereof. In this paper, we extend upon this second approach, exploring the use of independently calculated stellar densities to identify the most promising transiting exoplanet candidates.We use a set of CoRoT candidates and the set of known transiting exoplanets to examine the potential of this approach. In particular, we note the possibilities inherent in the high-precision photometry from space missions, which can detect stellar asteroseismic pulsations from which accurate stellar densities can be extracted without additional observations. © 2011 The American Astronomical Society. All rights reserved.

Ivison R.J.,Astronomy Technology Center | Ivison R.J.,University of Edinburgh | Swinbank A.M.,Durham University | Swinyard B.,Rutherford Appleton Laboratory | And 37 more authors.
Astronomy and Astrophysics | Year: 2010

We present a detailed analysis of the far-infrared (-IR) properties of the bright, lensed, z = 2.3, submillimetre-selected galaxy (SMG), SMM J2135-0102 (hereafter SMM J2135), using new observations with Herschel, SCUBA-2 and the Very Large Array (VLA). These data allow us to constrain the galaxy's spectral energy distribution (SED) and show that it has an intrinsic rest-frame 8-1000-μm luminosity, Lbol, of (2.3±0.2) × 10 12 L⊙ and a likely star-formation rate (SFR) of ∼400 M⊙ yr-1. The galaxy sits on the far-IR/radio correlation for far-IR-selected galaxies. At ≥70 μm, the SED can be described adequately by dust components with dust temperatures, Td ∼ 30 and 60 k. Using SPIRE's Fourier- transform spectrometer (FTS) we report a detection of the [C ii] 158 μm cooling line. If the [C ii], CO and far-IR continuum arise in photo-dissociation regions (PDRs), we derive a characteristic gas density, n ∼ 103 cm-3, and a far-ultraviolet (-UV) radiation field, G0, 103× stronger than the Milky Way. L[CII]/Lbol is significantly higher than in local ultra-luminous IR galaxies (ULIRGs) but similar to the values found in local star-forming galaxies and starburst nuclei. This is consistent with SMM J2135 being powered by starburst clumps distributed across ∼2 kpc, evidence that SMGs are not simply scaled-up ULIRGs. Our results show that SPIRE's FTS has the ability to measure the redshifts of distant, obscured galaxies via the blind detection of atomic cooling lines, but it will not be competitive with ground-based CO-line searches. It will, however, allow detailed study of the integrated properties of high-redshift galaxies, as well as the chemistry of their interstellar medium (ISM), once more suitably bright candidates have been found. © ESO 2010.

Riva M.,National institute for astrophysics | Barriere J.-C.,CEA Saclay Nuclear Research Center | Ferrand D.,Observatoire Astronomique de Marseille Provence | MacIaszek T.,Ctr. National dTudes Spatiales Toulouse | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

This paper presents the GWA and the Compensating mechanism of the Near Infrared SpectroPhotometer (NISP) instrument of the ESA Euclid mission. The NIS instrument should perform an exposure sequence in the wave- length range [0.9 - 2.0]um with different exposures of the same field of views with different passband grisms with two orthogonal dispersion directions and two wavelength range. These functionalities will be achieved by a mechanism supporting the optical elements: the Grism Wheel Assembly (GWA). The required positioning repeatability is in the order of few arcsec to keep the spectra aligned with the detector pixel columns/rows. The GWA will be assembled to the NISP Optomechanical Assembly (NIOMA) with an operating temperature of 140K. A further mechanism is necessary to compensate the torque perturbances induced by the two large wheels. It is based onto a stepper motor that will drive a flywheel. © 2012 SPIE.

Cuillandre J.-C.,Canada France Hawaii Telescope | Withington K.,Canada France Hawaii Telescope | Hudelot P.,CNRS Paris Institute of Astrophysics | Goranova Y.,CNRS Paris Institute of Astrophysics | And 11 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) is a high impact scientific program which will see its final official release open to the world in 2012. That release will seal the legacy aspect of the survey which has already produced a large collection of scientific articles with topics ranging from cosmology to the Solar system. The survey core science was focused on dark energy and dark matter: the full realization of the scientific potential of the data set gathered between 2003 and 2009 with the MegaCam wide-field imager mounted at the CFHT prime focus is almost complete with the Supernovae Legacy Survey (SNLS) team preparing its third and last release (SNLS5), and the CFHTLenS team planning the release based around the cosmic shear survey later this year. While the data processing center TERAPIX offered to the CFHTLS scientific community regular releases over the course of the survey in its data acquisition phase (T0001-T0006), the final release took three years to refine in order to produce a pristine data collection photometrically calibrated at better than the percent both internally and externally over the total survey surface of 155 square degrees in all five photometric bands (u*, g', r', i', z'). This final release, called T0007, benefits from the various advances in photometric calibration MegaCam has benefited through the joint effort between SNLS and CFHT to calibrate MegaCam at levels unexplored for an optical wide-field imager. T0007 stacks and catalogs produced by TERAPIX will be made available to the world at CADC while the CDS will offer a full integration of the release in its VO tools from VizieR to Aladin. The photometric redshifts have been produced to be released in phase with the survey. This proceeding is a general introduction to the survey and aims at presenting its final release in broad terms. © 2012 SPIE.

Hernandez-Lopez I.,National Institute of Astrophysics, Optics and Electronics | Athanassoula E.,Observatoire Astronomique de Marseille Provence | Mujica R.,National Institute of Astrophysics, Optics and Electronics | Bosma A.,Observatoire Astronomique de Marseille Provence
Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias | Year: 2010

A significant fraction of galaxies in the Local Universe classified as unbarred in the RC3 turn out to be barred in optical and NIR wavelengths. In the Local Group the Milky Way and M31 have shown to be barred as well, this also could be the case of M33. In this paper we present the results of the Ellipse fitting and bidimensional Fourier Analysis, on the R and I bands, deprojected and non-deprojected, images of M33 obtained from DSS2 and Spitzer-IRAC. © 2010: Instituto de Astronomía, UNAM.

Grupp F.,Max Planck Institute for Extraterrestrial Physics | Grupp F.,Ludwig Maximilians University of Munich | Pietroc E.,Observatoire Astronomique de Marseille Provence | Geis N.,Max Planck Institute for Extraterrestrial Physics | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

The ESA/EUCLID satellite is equipped with two instruments that are simultaneously observing patches of > 0:5 square degree on the sky. The VIS visual light high spacial resolution imager and the NISP near infrared spectrometer and photometer are separated by a di-chroic beam splitter. This paper shows the baseline concept of the NISP instrument with its two observational modes being low resolution slit-less spectroscopy and three band J, H& K+ photometry. The drivers for the optical design, the nominal performance as well as the tolerancing approach for NISP are being presented. The impact of the tolerance approach and the tight tolerances on the opto-mechanical design, assembly, integration and verification is addressed in a special section of this paper. © 2012 SPIE.

Loading Observatoire Astronomique de Marseille Provence collaborators
Loading Observatoire Astronomique de Marseille Provence collaborators