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Accueil > Le Laboratoire > Séminaires et conférences > Résumés

 Résumés

Remarque : les enregistrements des séminaires sont disponibles sur seminars.lam.fr.



28 June 2019 - 11h

  • TBD
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TBD

21 June 2019 - 11h

  • TBD
  • TBD

TBD

14 June 2019 - 11h

  • Vianney Lebouteiller (Laboratoire AIM - CEA Saclay)
  • TBD

TBD

7 June 2019 - 11h

  • Nicolas Prantzos (IAP)
  • TBD

TBD

24 May 2019 - 11h

  • Lutz Wisotzki (Leibniz Institut für Astrophysik Potsdam AIP)
  • TBD

TBD

17 May 2019 - 11h

  • TBD
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TBD

10 May 2019 - 11h

  • TBD
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TBD

3 May 2019 - 11h

  • TBD
  • TBD

TBD

26 April 2019 - 11h

  • Peter Capak (Caltech)
  • TBD

TBD

5 April 2019 - 11h

  • TBD
  • TBD

TBD

29 March 2019 - 11h

  • David Ehrenreich
  • TBD

TBD

22 March 2019 - 11h

  • Coralie Neiner (LESIA)
  • TBD

TBD

15 March 2019 - 11h

  • Sebastian Kamann (U. Liverpool)
  • TBD

TBD

8 March 2019 - 11h

  • Martin Crocce (IEEC-CSIC)
  • TBD

TBD

1 March 2019 - 11h

  • NISP Team (LAM)
  • TBD

TBD

8 February 2019 - 11h

  • Erika Hamden (U. Arizona)
  • TBD

TBD

1 February 2019 - 11h

  • Sera Markoff (API/GRAPPA, University of Amsterdam)
  • Imaging (and imagining) Black Holes

Black holes are one of the most exotic consequences of Einstein’s General Relativity, yet they are also very common players in the Universe, existing on scales ranging from the stellar up to beasts over a billion times more massive than our sun. Contrary to their reputation as cosmic vacuum cleaners, they actually serve as engines for extremely energetic processes, playing a major role in regulating the growth of galaxies. Some black holes also launch enormous jets of relativistic plasma that accelerate particles to energies millions of times higher than the Large Hadron Collider at CERN. Astronomers, astrophysicists and physicists all have reasons for wanting to understand black holes, yet we have been limited by the resolution of our telescopes from actually seeing one directly. This situation has changed dramatically with the coming of the Event Horizon Telescope, an Earth-sized array operating in the millimeter wavelength regime, that can actually make pictures of a couple of nearby supermassive black holes such as the one in our Galactic centre, Sgr A*, and the active galactic nucleus M87. I will briefly introduce the phenomenology of black hole accretion, and discuss some of the key problems we are still facing in terms of building a working model for these processes, and show some examples of the current cutting edge in modelling and interpretation. Along the way I will explain what the Event Horizon Telescope is, and how we anticipate the groundbreaking data from the first full run in April 2017 (note : I will not be able to show the results yet !) will help revolutionise our field and shed light on these complex environments.

25 January 2019 - 11h

  • Licia Verde (ICCUB)
  • The importance of bias

In cosmology bias is used in two different contexts. In one case it refers to systematic errors in a measurement or a determination of model’s parameters. In the other case it refers to the relation between the clustering of mass and that of observable tracers such as galaxies.
I will touch upon both aspects. I will highlight the importance of considering and modelling the effect of systematic errors and I will present a model of the halo bias in massive neutrinos cosmologies

18 January 2019 - 11h

  • Mark Sargent (Sussex)
  • Environment and interactions - How (not) to produce a starburst galaxy

Over the last 10 billion years the typical activity level of star-forming galaxies has decreased by more than an order of magnitude. Observations reveal that, at both low and and high redshift, there is a population of ’starburst’ galaxies that are significantly more active than the bulk of the rest of the population. Despite being comparatively rare, these starbursts are among the most popular targets for detailed studies of astrophysical processes, by virtue of being bright and thus readily observable. But what does it take to produce a starburst event during the peak epoch of galaxy formation at z 2, when even the average star-formation rate of the star-forming galaxy population was as high as locally observed only for the most extreme starbursting systems ?
In my talk I will present new measurements of the composition of the starburst population at z<2, in terms of its split into ’normal’ and interacting or merging galaxies. I will also review how a high star-formation efficiency - one of the trademarks of starburst events - is linked to galaxy environment based on the increasing body of literature on the interstellar medium in high-z galaxy clusters. Finally, I will discuss how measurements of host galaxy star-formation efficiency can provide clues on the interplay between starburst and AGN activity.

7 December 2018 - 11h

  • Pierre Beck (IPAG)
  • Shedding light on the darkest Solar System objects

Comets and most asteroids are extremely dark objets. They typically reflect only a few percent of the incoming light. I will discuss the nature of dark Solar System small bodies based on ground-based observations, in situ observation (i.e. VIRTIS / ROSETTA) and laboratory measurements. I will discuss in particular the case of C-type near-Earth asteroids, which are being targetted by two sample-return missions and how they might (or not) be representative of the main-belt population. Finally, I will discuss the case of cometary nuclei, possessing a peculiar absorption around 3-µm as observed by VIRTIS/ROSETTA. I will discuss how cometary nuclei relate to asteroid spectral-type and the nature of this spectral feature.

30 November 2018 - 11h

  • Chiara Caprini (APC Paris)
  • Cosmology with LISA

Gravitational waves can constitute a unique probe of both the early and late-time universe. After a general introduction to the subject, this seminar focuses on the potential of the space-based interferometer LISA to test cosmology. In particular, two aspects will be discussed : the stochastic gravitational wave background generated by sources in the very early universe, and the use of compact binaries, emitting gravitational waves, as standard sirens, i.e. to probe the energy content and the acceleration of the late-time universe.

23 November 2018 - 11h

  • Andrea Ferrara (SNS, Pise)
  • The Interstellar Medium of High Redshift Galaxies

In the last decade we have explored the cosmic depths and found a statistically significant number of galaxies well into the Epoch of Reionization. However, our physical knowledge of these pristine objects remains very scant. Investigating the internal structure, interstellar medium and evolution of early galaxies is the next challenge to understand key processes as the cosmic history of baryons, feedback, reionization and metal enrichment of the intergalactic medium, This ambitious plan can be tackled by combining a new generation of physically-rich, high resolution, zoom simulations with data in the sub-mm bands provided by ALMA. This approach will be soon strengthened by the forthcoming JWST power. I will review the present status and the open questions in the field.

16 November 2018 - 11h

  • Joel Vernet (ESO)
  • A multi-phase study of the Circum Galactic Medium in High-z radio galaxies with MUSE and ALMA

Radio galaxies (radio loud type-2 AGN) are among the most massive and luminous galaxies known at any redshift. They are found in high density environments (proto-clusters) and since the 1990s, it is known that they are surrounded by massive haloes extending to 150-200 kpc. These emission-line haloes extend well beyond the boundaries of the host galaxy, and form the link between its inter-stellar medium and the intra-cluster gas in the proto-cluster environment, i.e. the Circum Galactic Medium (CGM). They may well represent the accretion flows feeding the host galaxies with primordial gas from filamentary large-scale structures. The AGN is the flashlight illuminating and revealing these structures which play a crucial role in the galaxy formation process.
In this talk, I will present the results of an on-going VLT/MUSE and ALMA study of a sample of radio galaxies at 3<z<4.5 aimed at drawing a complete picture of the nature of these giant haloes in all possible phases : ionized, molecular, atomic, neutral.

9 November 2018 - 11h

  • Coralie Neiner (LESIA)
  • TBD

TBD

26 October 2018 - 11h

  • TBD
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TBD

19 October 2018 - 11h

  • Vanessa Bailey (JPL)
  • Status and Potential Scientific Capabilities of the WFIRST Coronagraph Instrument

The Coronagraph Instrument (CGI) for NASA’s Wide Field Infrared Survey Telescope (WFIRST) will constitute a dramatic step forward for high-contrast imaging, integral field spectroscopy, and polarimetry of exoplanets and circumstellar disks, aiming to improve upon the sensitivity of current direct imaging facilities by 2-3 orders of magnitude. Furthermore, CGI will serve as a pathfinder for future exo-Earth imaging and characterization missions by demonstrating wavefront control, coronagraphy, and spectral retrieval in a new contrast regime, and by validating instrument and telescope models at unprecedented levels of precision. I will discuss the status of the instrument design, some of its key new technologies, and its potential science yield.

12 October 2018 - 11h

  • TBD
  • TBD

TBD

5 October 2018 - 11h

  • Benoit Neichel (LAM)
  • HARMONI au LAM : science, optique adaptative, designs, réalisations et intégrations

HARMONI est l’un des 3 instruments de première lumière qui équipera l’Extremely Large Telescope Européen, le futur télescope Européen de 39m de diamètre. HARMONI est un spectrographe à intégral de champ (IFU), mono-objet, qui observera dans la gamme visible et proche infra-rouge (de .5 à 2.4 microns). HARMONI fournira une résolution spectrale de R=3000 à R=20000, et une résolution angulaire de 60 à 4 mas. Pour exploiter pleinement la limite de diffraction de l’E-ELT, HARMONI sera équipé de deux systèmes d’Optique Adaptative (OA). Le premier est un système d’OA classique (SCAO) et le deuxième sera un système d’OA grand champ, assisté par étoiles lasers (LTAO). HARMONI s’inscrit dans la lignée d’instruments qui équipent le VLT, tels que SINFONI ou MUSE, et la première lumière est prévue pour 2025. Les cas scientifiques principaux d’HARMONI couvrent un large spectre, depuis l’étude et la caractérisation des exo-planètes, l’étude des populations stellaire dans les galaxies proches, et jusqu’aux galaxies à grand décalage vers le rouge. HARMONI regroupe un consortium de 6 laboratoires, dont 2 Français (LAM et CRAL). Les équipes du LAM sont en charge de la réalisation de plusieurs sous-systèmes, dont les analyseurs de surface d’onde pour l’optique adaptative.
Dans cette présentation, nous donnerons un statut du projet HARMONI et des développements actuellement en cours au LAM. En particulier, on détaillera quelques cas scientifiques d’intérêt pour les chercheurs du LAM, on présentera le concept d’instrument et son Optique Adaptative, on développera les designs réalisés par les équipes techniques du LAM et on abordera le planning de l’instrument, et les phases de tests qui se réaliseront au LAM. HARMONI est l’un des grands projets développé au LAM, et ce séminaire, à l’attention de tous les personnel du laboratoire, sera l’occasion de mettre en avant les contributions du LAM et d’échanger avec les personnels impliqués dans le projet.

28 September 2018 - 11h

  • Bernard Marty (CRPG Nancy)
  • TBD

TBD

14 September 2018 - 11h

  • Caroline Dorn (Univ Zurich)
  • Interior characterization in multiplanetary systems : TRAPPIST-1

I will start with a general introduction to the interior characterization of exoplanets. There are two kinds of data available for interior characterization. There are astrophysical observations that provide us planetary mass and radius for example, and there are data informed from theory or experiments. Both kinds of data are generally few with large uncertainties. By using Bayesian inference analysis, these uncertainties can be formally taken into account.
In a second part, I will focus on the specific case of TRAPPIST 1. Interior characterization traditionally relies on individual planetary properties, ignoring correlations between different planets of the same system. We explore such correlations and data specific to the multiplanetary-system TRAPPIST-1 and study their value for our understanding of their formation and evolution.



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