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Accueil > Le Laboratoire > Séminaires et conférences > Past Seminars > Résumés 2013-2014

 Résumés 2013-2014

20 June 2014 - 11h

  • Antonino Francesco Lanza (INAF/Catania)
  • Interactions between late-type main-sequence stars and close-in planets

I shall briefly review some topics related to tidal and magnetic interactions in systems consisting of close-in planets orbiting late-type main-sequence stars. In particular, I shall consider the relationship between the rotation period of the host star and the orbital period of the innermost planet found with Kepler data and discuss the explanations that have been proposed for it. Future timing observations of planetary transits can be used to discriminate between the proposed models because they are based on remarkably different tidal dissipation rates. I shall consider also magnetic star-planet interactions by introducing some recent observations and discussing some proposed models. The problem of the evolution of the rotation of stars with close-in massive planets will also be addressed in the context of recent results.

13 June 2014 - 11h

  • Roland Bacon (CRAL)
  • Highlights from the Multi Unit Spectroscopic Explorer (MUSE)

The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation VLT panoramic integral-field spectrograph. MUSE has a field of 1×1 arcmin² sampled at 0.2×0.2 arcsec² and a simultaneous spectral range of 0.465-0.93 µm, at a resolution of R 3000. The instrument has been designed to take advantage of the VLT ground layer adaptive optics ESO facility using four laser guide stars. MUSE couples the discovery potential of a large imaging device to the measuring capabilities of a high-quality spectrograph, while taking advantage of the increased spatial resolution provided by adaptive optics.
After a successful preliminary acceptance in Europe in fall 2013, MUSE has been dismounted, shipped to Chile and re-integrated in the Paranal new integration hall and finally installed on the Nasmyth platform of UT4 late January this year. During the 2 commissioning runs, millions of spectra have been obtained in order to validate the instrument and measured its achieved performance. To demonstrate its power, a number of show-case and spectacular observations have also been obtained. Preliminary results demonstrate that MUSE is likely to become a new reference in the field of integral field spectroscopy thanks to its large field of view, very high throughput, excellent image quality, good spectral resolution, wide simultaneous spectral range and state-of-the art control and data reduction software

6 June 2014 - 11h

  • Rosetta Consortium
  • Rosetta : le chasseur de comète

La sonde Rosetta de l’Agence Spatiale Européenne (ESA) est actuellement en route vers la comète 67P/Churyumov-Gerasimenko, qu’elle atteindra cet été. Le Laboratoire d’Astrophysique de Marseille (LAM) est l’un des principaux laboratoires français impliqués dans la mission Rosetta avec le soutien du Centre National d’Etudes Spatiales (CNES). La caméra OSIRIS a été en partie réalisée au LAM, grâce au savoir faire des techniciens et ingénieurs du laboratoire. Cette caméra fournira des images d’une très haute résolution spatiale, sans aucun doute spectaculaires. La collecte des images et leur analyse scientifique constitueront des événements phares des années 2014 et 2015 pour le LAM. A cette occasion, nous présenterons au cours de ce séminaire un état de l’art des connaissances sur les comètes et un historique de la mission Rosetta depuis ses débuts jusqu’aux dernières images de la comète prises il y a quelques jours.

23 May 2014 - 11h

  • Marta Volonteri (IAP)
  • The early evolution of massive black holes

Massive black holes, weighing millions to billions of solar masses, inhabit the centers of today’s galaxies. The progenitors of these black holes powered luminous quasars within the first billion years of the Universe. The first massive black holes must therefore have formed around the time the first stars and galaxies formed and then evolved along with their hosts for the past thirteen billion years. I will discuss some aspects of the cosmic evolution of massive black holes, from their formation to their growth and the interplay between black holes and galaxies.

16 May 2014 - 11h

  • Jean-Philippe Berger (ESO)
  • Protoplanetary disks at astronomical unit scale with PIONIER-VLTI

Planet formation processes occur in the inner astronomical units of protoplanetary disks and currently escape direct observation of most single-dish telescopes. PIONIER at VLTI provides sufficient sensitivity and precision to resolve the inner disk structure (e.g milli-arcsecond resolution) of the brightest intermediate mass young stellar objects (the so-called Herbig AeBe stars). It therefore offers a remarkable overlap with current ALMA and adaptive optics target lists. I will present the preliminary results of a PIONIER Large Program survey that allowed us to observe 54 stars and resolve in most of cases their near-infrared emission. We are therefore in a position to 1) reconstruct images of the inner disk emission 2) study statistically the morphology and temperature of the disk inner rims and relate these to the properties of the central stars, considerations on the disk structure and dust composition and evolutionary status. Additionally I will shortly introduce the current status of VLTI second generation instrumentation and their scientific goals.

18 Apr 2014 - 11h

  • Julien Grain (IAS Orsay)
  • Inflation, primordial gravity waves, and PLANCK and BICEP2

The american experiment BICEP2 recently claimed a detection of the so-called polarized B-mode of the CMB anisotropies at angular scales of the order of a degree. Such a signal could be interpreted as the footprint of primordial gravity waves on the cosmic microwave background, and is oftenly said to be a smoking-gun signature of primordial inflation. The aim of this seminar will be to make the statement « B-mode is a smoking-gun signature of inflation » more explicit. As a starting point, I will propose a very brief and general overview of the link between primordial inflation and the polarized anisotropies of the CMB : the key point is that gravitational waves are produced during inflation, and they are the sole source of B-mode in the CMB anisotropies at large angular scales. Then, the main idea and physical motivations for a phase of primordial inflation will be introduced, with a specific focus on the physical mechanism at the origin of primordial gravitational waves and underlining their quantum nature. I will finally discuss how CMB anisotropies can be used to set constraints on inflation showing the examples of PLANCK and BICEP2.

11 Apr 2014 - 11h

  • Eugene Vasiliev (Southern Federal University, Russia)
  • Life and adventures of binary SMBHs

I will review our present understanding of the evolution of binary supermassive black holes - how do they form, why do they merge into a single Eventually black hole, and what happens Afterwards, as well as the Chat as possible observational signatures and prospects of detection.

28 Mar 2014 11h

  • Françoise Combes (l’Observatoire de Paris LERMA)
  • Molecular Gas and Star Formation Across a Hubble Time

The cosmic star formation rate reveals a pronounced peak 10 Gyrs ago (or z=1-2) and then slows down, dropping by more than a factor 10 since z=1. This behaviour might be the result of combined physical processes, like hierarchical merging of galaxies, gas accretion, formation of molecular clouds and stars, metal enriched gas outfows that are driven by stellar winds, supernovae and AGN activity. I will review some IRAM recent results about the molecular content of galaxies and its dynamics, obtained from CO lines. The star formation efficiency increases with redshift, as shown by the Kennicutt-Schmidt law, and the derived depletion time. In massive galaxies, the gas fraction was higher in the past, and galaxy disks were more unstable and more turbulent. Preliminary results will be shown with ALMA, which will in the future allow the study of main sequence galaxies at high z with higher spatial resolution and sensitivity.

21 Mar 2014 - 11h

  • Vivienne Wild (St. Andrews)
  • The Evolution of Starburst Galaxies

Massive bursts of star formation represent a transient, and perhaps infrequent phase in the life of massive galaxies, and it is currently thought that the majority of stars in the Universe are formed in a more "quiescent" mode of star formation. However, mergers between gas rich galaxies triggering starbursts at high redshift are a leading candidate for the near-coincident morphological and spectral disruption required to build red elliptical galaxies. I will start this talk with a case study : the Mice merger, recently observed as part of the CALIFA integral field survey. I will then turn to statistical samples, that can be used to track the properties (black hole accretion, star formation, dust and gas content) of starburst galaxies for up to a Gyr following the triggering event. Finally, I’ll look towards the future : quantifying precisely the contribution of gas-rich mergers to the birth and growth of elliptical galaxies.

14 Mar 2014 - 11h

  • Melissa Ness (MPIA)
  • The New Formation of the Galactic Bulge of the Milky Way

Galactic bulges are signatures of Galaxy formation, as different kinds of bulges are formed in different ways. Understanding the bulge of the Milky Way and its formation places strong constraints on which processes have been dominant in the evolution of the Milky Way, and disk galaxies in general. Our understanding of the formation of the bulge of the Milky Way has changed in the last few years. The formation scenario has shifted from one emphasising the bulge as a distinct population in the Milky Way, formed via mergers or dissipational collapse, before the disk, to one where dynamical formation from the disk is considered to play an important role. I will present the latest observational results for the bulge that have driven this change, demonstrate why models are key for interpretation of observational data and highlight the outstanding questions that will be addressed by new surveys.

21 Feb 2014 - 11h

  • Simone Esposito (Arcetri Astrophysical Observatory)
  • Observing at the Large Binocular Telescope : The Power of Adaptive Optics

The Large Binocular Telescope (LBT) is a unique telescope featuring two co-mounted optical trains with 8.4m primary mirrors. The telescope First Light Adaptive Optics system (FLAO) uses two innovative key-components, namely an adaptive secondary mirror with 672 actuators and a high order pyramid wavefront sensor. On-sky operations demonstrated that this system reached a performance level never achieved before on a ground based large optical telescope. Images with 40mas resolution, Strehl-Ratio (SR)>90% and contrast around 10^4 has been acquired in H band (1.6 um). In the seminar, after describing shortly the LBT telescope main features and the FLAO system and its commissioning, I will present some scientific results achieved in SDT AO mode such as the imaging of exoplanets (HR8799), CMDs of crowded globular clusters regions (M92, M15), and high resolution astrometry of theta 1 Ori cluster in Trapezium region. Finally, I will summarize the proposed future developments of LBT AO systems and instrumentation.

13 Feb 2014 - 11h

  • Matthieu Béthermin (ESO Garching)
  • Understanding the High-z, Dusty, Star-Forming Galaxy Populations

The star formation rate (SFR) density was more than 10 times higher at z=2 than nowadays. In addition, the star formation was dominated by objects forming 100Msun/yr. This strong evolution is very difficult to explain with physical models. Observations and phenomenological models can thus provide crucial insights to explain this. I will review the new results obtain using a new modeling approach called 2SFM (2 star-formation mode). This modeling approach is based on the existence of a strong correlation between the stellar mass and the SFR, so-called main sequence, suggesting that the bulk of the star formation in the galaxies is driven by secular processes. However, a second population of major-merger-driven starburst, with a boosted star formation efficiency, is necessary to explain the most extreme objects.
This approach is very efficient to reproduce a large number of statistical observables as the infrared luminosity functions and the number counts of galaxies from the mid-IR to the radio assuming just a set of observed scaling laws. With few extra assumptions concerning the relation between the dust attenuation and the stellar mass, we are also able to reproduce the UV luminosity functions. We also extended this model to predict the link between the dark matter halos and the star-forming galaxies using a technique of abundance matching, and managed to reproduce the fluctuations of the cosmic infrared background, measured by Planck and Herschel and caused by the fact that star-forming galaxies follow the large-scale structures. In this paradigm, the strong evolution of star-forming galaxies can be explained by an universal halo mass where the star-formation is the most efficient and the evolution of the accretion into halos at this mass. This model also agrees well with our new extensive study of the clustering of UV- and FIR-selected at z 2 as a function of their physical properties, which also provide interesting constraints on the nature of starbursts and the mechanisms of quenching of galaxies at high redshift and. Finally, I will present new results on the evolution of the mean infrared SEDs of main-sequence galaxies and starbursts up to z=4 and the consequences on their dust and gas content. These results suggest that the main causes of the evolution of the star formation at high redshift is the presence of massive reservoirs of gas, rather than an evolution of the star formation efficiency.

31 Jan 2014 - 11h

  • Romain Teyssier (Zürich)
  • Modelling feedback processes in galaxy formation simulations

Galaxy formation was first believed to proceed through hierarchical merging, gas cooling angular momentum conservation in a well defined equilibrium dark matter hole. This rather quiescent view of spiral galaxy formation was at odd with observation of the distant universe, where strong winds and violently unstable disks are seen, rather than nice razor sharp spiral disks. A new picture is emerging in which violent feedback processes are playing the dominant role in determining galaxy properties. These feedback processes seem to be different for each mass scale, with supernovae feedback dominating the formation of dwarf galaxies, radiative feedback mostly at play in large spirals and supermassive black holes feedback in galaxy clusters and giant ellipticals. I will present some recent results obtained at these various scales using cosmological simulations and outlining the successes and failures of the models.

24 Jan 2014 - 11h

  • Laurène Jouve (IRAP)
  • What do Numerical Simulations Teach Us About the Magnetism of Our Star ?

Stars and particularly our Sun are highly turbulent magnetic objects. The magnetic field observed at the surface of the Sun is thought to be generated in deeper layers by the solar dynamo. This mechanism would be in particular responsible for the regular inversion of the magnetic field : the 22-year cycle. By modeling the different stages of the solar dynamo, we will show how the evolution of the magnetic field generated in the solar plasma can create such surface activity. We will present in this seminar 2D and 3D simulations that help to understand, on one hand, how the large scale flow affects the whole magnetic cycle, and, on the other hand, which mechanisms create the intense magnetic structures in the depths of the Sun that emerge on the surface and form active regions.

17 Jan 2014 - 11h

  • Albert Bosma (LAM)
  • SKA Precursors

The SKA project started in the early nineties, when people began to think on how to image the 21-cm line distribution in galaxies at what was then high redshifts. It was then decided to augment the effective area of a synthesis telescope by a factor 100 compared to then existing ones. Hence, the idea to construct a Square Kilometer Array (SKA).
From the outset, new telescope designs and new ways of doing radioastronomy were envisaged. The project went through various phases, and is now so mature that a site decision has been made, and the headquarters of the SKA-organization been built. 10 member countries and 1 observer country are currently funding the SKA operations. A road map is being executed to arrive at partial operation by 2020 or so.
To arrive at the SKA, pre-cursors and pathfinder telescopes are already in operation or now under construction. In this talk, I will give an overview of the scientific areas for which the SKA or even its precursors will transform the field. I will adopt a historical approach, and highlight past successes of radio astronomy, their current impact, and future discoveries waiting to be made. I will emphasize one key aim underlying much of radio astronomy : serendipitous discoveries, and the exploration of the unknown. A lot of the material will be at a review level.

13 Dec 2013 - 11h

  • Quentin A. Parker (Macquarie University)
  • The New Macquarie PN Database : A Multi-Wavelength Window Into the Soul of Late-Stage Stellar Evolution

A description of the importance of Planetary Nebulae (PN) in late stage stellar evolution will be presented with particular emphasis on PN research at Macquarie University where we have also created a new, comprehensive, multi-wavelength database of all currently known PN, including the latest MASH and IPHAS discoveries. This powerful database is currently being installed at the CDS in Strasbourg for community use. The database provides, where available, access to over 40 types of multi-wavelength images ranging from GALEX in the UV through broad and narrow band optical images to the NIR and MIR and then out to the radio. The best data from the latest wide-field ground and space-based surveys is employed. Spectra, including from powerful new integral field instrumentation, newly updated (and corrected) positions and other pertinent information (including, where available our accurate new line fluxes) for all known Galactic PNe are provided. The database is in a form that can be easily interrogated and selected against using the extensive parameter list according to multiple, user specified values and standard SQL. Fresh insights and new diagnostic capability is encapsulated within this convenient, one-stop-shop for PNe visualisation and study.

12 Dec 2013 - 11h

  • Didier Barret (IRAP Toulouse)
  • Athena : The First Deep Universe X-ray Observatory

The Advanced Telescope for High-energy Astrophysics (Athena) will be proposed to ESA as the L2 mission scheduled for a launch in 2028. It is specifically designed to answer two of the most pressing questions for astrophysics in the forthcoming decade : How did ordinary matter assemble into the large scale structures we see today ? and how do black holes grow and shape the Universe ? For addressing these two issues, Athena will provide transformational capabilities in terms of angular resolution, effective area, spectral resolution, grasp, that will make it the most powerful X-ray observatory ever flown by far. A lightweight X-ray telescope based on ESA’s Silicon Pore Optics technology provides large effective area (2 square meter) with excellent angular resolution (5 arc second), combining with state-of-the-art instrumentation for spatially resolved high resolution X- ray spectroscopy (2.5 eV spectral resolution as provided by the X-ray Integral Field Unit, X-IFU) and wide field X-ray imaging (40 x 40 ‘ field of view as provided by the Wide Field Imager, WFI), which also provides sub-millisecond timing capability for bright sources. Such an observatory, when opened to the astronomical community, will be used for virtually all classes of astrophysical objects, from high-z gamma-ray bursts to the closest planets in our solar neighborhood. Athena will guarantee a transformation in our understanding of The Hot and Energetic Universe, and establish European leadership in high-energy astrophysics for the foreseeable future. In this talk, I will review the core science objectives of Athena, present the science requirements and the foreseen implementation of the mission. I will illustrate the transformational capabilities of Athena compared to existing facilities, and discuss the foreseen French contribution to the X-ray Integral Field Unit.

29 Nov 2013 - 11h

  • Daniel Kunth (IAP)
  • Lyman Alpha Emitters : Local and Distant

Lyman Alpha Emitters (LAEs) are among the best tracers of distant galaxies and are especially suited for exploring the faint end of the luminosity function of Lyman Break Galaxies. They allow to map large structures, explore the impact of massive star formation onto the ISM and IGM, and question the role of dwarf galaxies to the re-ionisation of the Universe at z of 6-7. However LAEs form an heterogeneous class of objects since the Lyman alpha line is imprinted by the properties of the ISM medium in these galaxies. As such, studies of local LAEs with high spatial and spectroscopic details are of great importance. I’ll review their properties and will emphasize the need to challenge and propose projects for UV astronomy in the near future.

21 Nov 2013 - 11h

  • David Crampton (Herzbery Astrophysics/NRC Canada)
  • An Exciting Future for CFHT

Extremely large datasets are required to tackle most of the Big Questions confronting astronomy today, especially those involving Dark Energy, Dark Matter, Dark Halos, and Galaxy Evolution. Several projects are underway to provide imaging surveys at a variety of wavelengths (e.g., GAIA, LSST, Euclid, SKA) but complementary spectroscopic data are required to realize their potential. France and Canada have the opportunity to transform their investment in CFHT into exactly what is required : thanks to the design of the infrastructure of the original CFHT, it can be straightforwardly upgraded to a 10m, highly multiplexed, wide field spectroscopic facility (“ngCFHT”). With an expanded partnership, the capital cost to France would be comparable to that of a modern large instrument for an 8m telescope. The CFHT SAC and Board agree that the science case for ngCFHT is outstanding and compelling. The next step will be the formation of a Project Office to assist in the development of a new partnership and to bring the design of ngCFHT to construction readiness. This presents an exciting opportunity for significant contributions from French scientists and engineers because they are already familiar with CFHT, and have experience and expertise in constructing powerful spectroscopic instruments. ngCFHT will build on the outstanding legacy of CFHT to deliver world-leading science at very modest cost.

15 Nov 2013 - 11h

  • Matthew Auger (Cambridge)
  • Telescopes the Size of the Universe : Measuring Structures from 100pc to Gpc Scales with Gravitational Lenses

Strong gravitational lensing is very similar to lensing from an optical bench in the laboratory, and I will review how investigations of the properties of this `optical system’ — including the strength of the lens and the distances between the observer, lens, and source — can provide insights into dark matter and dark energy. In particular, I will briefly present the most recent results on measuring galaxy-scale dark matter substructures (which manifest as imperfections in the lens), inferring the stellar mass-to-light ratios in galaxies (which indicate that the stellar initial mass function may be non-universal), and determining the structure of dark matter halos on galaxy and cluster scales (which may be a diagnostic of central feedback processes). Finally, I will briefly review the current status and future prospects of measuring cosmological distances — and therefore properties of the accelerated-expansion of the Universe — using strong lenses.

8 Nov 2013 - 14h

  • Pierre Baudoz (LESIA/Observatoire de Paris)
  • What’s Next for High-Contrast Imaging of Exoplanets ?

The architecture of exoplanetary systems is relatively well known inward to 5 AU thanks to indirect techniques, which have allowed characterization of about 1000 exoplanets orbits, masses and sometimes radii. The next step is the characterization of exoplanet atmospheres at long period, which requires direct imaging capability. However, planets are much fainter than their star at any wavelengths and angularly very close. One solution is to observe young planets that have not yet cooled down from formation processes. A handful of these young giant planets have been discovered recently by direct imaging. More discoveries of young giants at large separations (> 5AU) around nearby stars (<50-100pc) are anticipated with the next generation of coronagraphic instruments on 8-m class telescopes (SPHERE, GPI, SCExAO) to be installed next year. In the longer term, the spectroscopic study of mature giant planets and lower mass planets (Neptune-like, Super Earths) will require the achievement of even larger contrasts (109-1010) at closer separations (1 AU or so). In this seminar, I will show what has been done so far to study a few key points mandatory to reach such large contrasts like unbiased wavefront control at picometer level, achromatic coronagraphy and differential imaging. I will then describe the tools (R&D test bench, end-to-end software) we are developing at LESIA to prepare these instruments, emphasizing the results obtained on the R&D bench we have been developing for the last 5 years.

18 Oct 2013 - 11h

  • Julien Grain (IAS Orsay)
  • Quantum Gravity in the Cosmic Microwave Background

Loop quantum cosmology, although speculative, imposed itself recently as a promising description of our Universe at Planck scales. Maybe loop quantum cosmology is less an application of loop quantum gravity than a genuine topic of research in and of itself, used to tackle problems proper to cosmology ; it is not currently the result of the passing to the limits of loop quantum gravity but more of a theoretical framework already lying in a certain limit. In this framework, both problems of the big bang singularity and the contrived nature of inflation are resolved. The result is a regular big bounce instead of the big bang, followed by an inflation phase. I will show to which extent such a bounce would leave an observational imprint on the anisotropies of the Cosmic Microwave background. Eventually, I will sketch how loop quantum cosmology could be constrained by the measurements of the CMB.

11 Oct 2013 - 11h

  • Niranjan Thatte (Oxford)
  • HARMONI : the first light, visible and near-IR integral field spectrograph for the ELT

ELT, the world’s largest ground based telescope, to be located at Cerro Armazones in Chile, will be equipped with two instruments at first light - a camera and a spectrograph. I will present HARMONI, the visible and near-IR integral field spectograph — a work-horse, versatile instrument that will cater to a wide range of observing programmes. I will present the capabilities of HARMONI, and highlight several key science areas where it can expect to make a big impact, combining the huge collecting area & unprecedented spatial resolution of the ELT. HARMONI is optimally suited to carry out detailed, spatially resolved studies of extended objects to unravel their morphology, kinematics, and chemical composition, whilst also enabling ultra-sensitive observations of point sources. I will also present the HARMONI instrument concept in some detail, including refinements since the end of Phase A.

8 Oct 2013 - 11h

  • Varsha Kulkarni (University of South Carolina)
  • Quasar Absorption Systems as Probes of Galaxy Evolution

The evolution of galaxies and the cosmic history of element production are fundamental themes in modern astrophysics and cosmology. However, the light emitted by distant galaxies is often too faint to allow detailed studies. Absorption lines in quasar spectra can be used to probe interstellar gas in galaxies at various stages of evolution, and thus provide powerful probes of the history of star formation and chemical enrichment in galaxies. This technique has revealed a ``missing metals problem’’ in low-redshift galaxies, i.e. a discrepancy between the observed amount of metals and the amount predicted by the chemical evolution models. On the other hand, there is a population of galaxies with very high levels of metals, including some that had reached several times the solar metallicity 7-10 billion years ago. What is the nature of these galaxy populations, and what caused the different levels of chemical enrichment ? We will discuss clues emerging from imaging/ spectroscopic observations that promise to shed light on these and other aspects of galaxy evolution. We will also discuss observations of interstellar dust in the quasar absorbers, and implications for dust grain composition in distant galaxies.

4 Oct 2013 - 11h

  • Benoit Neichel (LAM)
  • Wide-Field Adaptive Optics for ground based telescopes : First science results and new challenges

Over the 20 past-years, Adaptive Optics [AO] for astronomy went from a demonstration phase, to a well-proven and operational technique. Since the first astronomical AO systems were opened to the community in the early 1990s, numerous technical achievements have been accomplished, and it is now inconceivable to consider building a large telescope without AO. AO observations have brought some of the major discoveries in astronomy with, among others, detailed study of the massive black hole at the center of our Galaxy, detailed images of the surface of solar systems planets, or precise morphology and dynamics of very distant galaxies.
We are today at the beginning of a new step forward, with the birth of a revolutionary generation of AO systems called Wide Field AO [WFAO]. By using multiple Laser Guide Stars [LGS], WFAO significantly increases the field of the AO corrected images, and the fraction of the sky that can benefit from such correction. Therefore, where the first AO systems were well suited for observations of bright and relatively small objects, the new generation of WFAO is opening the path for a multitude of new science cases.
In this presentation, I will present GeMS, the Gemini Multi-Conjugate Adaptive Optics System, which is the first WFAO instrument offered to the community. After a brief review of the principles of AO and the extension to WFAO, we will see the first images and science results obtained by GeMS. Finally, we will see how instruments like GeMS are paving the way for the future generations of Extremely Large Telescopes [ELTs].

27 Sep 2013 - 11h

  • Pierre Ferruit (ESA/ESTEC)
  • The James Webb Space Telescope and its instrument suite

Often presented as the successor of the Hubble Space Telescope (HST), the James Webb Space Telescope (JWST) will be one of the major space observatories of the next decade. This passively cooled 6.5-meter telescope will include a suite of 4 instruments providing imaging and spectroscopic capabilities from 0.6 to 27 microns. It is scheduled for launch in 2018 and is the result of the collaboration between the American (NASA), European (ESA) and Canadian (CSA) space agencies. In this seminar, I will first give an overview of the JWST mission and of its latest status. I will then focus on its 4 instruments (NIRCam, NIRSpec, NIRISS and MIRI) and their capabilities.

20 Sep 2013 - 11h

  • Emeric Le Floc’h (CEA Saclay)
  • Signatures of Cosmic Star Formation from Long GRBs : Old Fears and New Hopes

While the association between Long GRBs (LGRBs) and the collapse of massive stars is now firmly established, our perspectives for using LGRBs as unbiased cosmic probes of star formation are still highly debated. On one hand, the vast majority of LGRBs with sub-arcsec localizations has been observed toward low-mass and blue galaxies with only modest Star Formation Rates (SFR<10Msun/yr). This has been interpreted as the evidence for LGRBs to be favored in low-metallicity environments, hence introducing a bias toward galaxies with a chemically young ISM. On the other hand, some of the so-called "dark GRBs" are now pinpointing more massive and dusty host galaxies, which challenges our understanding of the link between GRBs and star formation in the distant Universe. I will review the most recent results on this topic, which include our very first detection of CO molecular gas in an LGRB host galaxy. I will discuss how these data could open a new window on the use of GRBs as star formation tracers at high redshift, and I will finally present the best observing strategies to adopt in the light of future GRB experiments like SVOM.

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