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Nombre de programmes trouvés : 552
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le (1h3m38s)

THE WARPED SIDE OF THE UNIVERSE: NUMERICAL RELATIVITY, GRAVITATIONAL WAVES AND MACROSCOPIC QUANTUM MECHANICS

There is a "Warped side" to our universe, consisting of objects and phenomena that are made solely or largely from warped spacetime. Examples are black holes, singularities (inside black holes and in the big bang), and cosmic strings. Numerical-relativity simulations are revolutionizing our understanding of what COULD exist on our universe's Warped Side; and gravitational-wave observations (LIGO, VIRGO, LISA, ...) will reveal what phenomena actually DO exist on the Warped Side, and how they behave.To detect the gravitational waves and extract their information, in ...
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le (59m6s)

STAR FORMATION IN THE DESERT: PROBING THE LOW-DENSITY EXTREMES

Over the past decade multi-wavelength observations have revealed the extraordinary ubiquity and diversity of star formation in galaxies, ranging over billionfold ranges in star formation rates (SFRs), whether expressed in absolute terms, or in terms of areally or mass-normalised SFRs. Considerable attention has been focussed on the high-density extremes in starbursts and galactic nuclei, but much can be learned as well from star formation in low-density regimes-- in the outermost discs of spiral galaxies, and in early-type galaxies, low surface brightness galaxies, and extreme ...
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le (1h1s)

STELLAR DYNAMICS AT THE CENTERS OF GALAXIES

The massive black holes found at the centers of most galaxies, including our own, are believed to be the ashes of the fuel that powered quasars early in the life of universe. I will briefly review some of the astronomical evidence for these objects and then describe some of the exotic dynamical phenomena that originate in their vicinity, including hypervelocity stars, resonant dynamical relaxation, phase transitions, and lopsided stellar disks.
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le (1h3m19s)

CHARTING THE TRANSIENT SKY: THE PALOMAR TRANSIENT FACTORY

Only about a hundred years ago astronomers came to recognize cosmic explosive events. What was once termed as Stella Nova are now divided into two major families, novae and supernovae (with real distinct classes in each). The variables and the explosions have been interesting in their own right and contributed richly to key problems in modern astrophysics: distances to galaxies and cosmography. The area of transient and variable stars is once again undergoing a renaissance due to wide field optical surveys.The Palomar Transient Factory (PTF) was ...
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le (56m47s)

SECRET LIFE OF SPACETIME

Combining the principles of general relativity and quantum theory still remains as elusive as ever. Recent work, that concentrated on the points of conflict and contact between quantum theory and general relativity, suggests a new perspective on gravity. It appears that the field equations of gravity in a wide class of theories - including, but not limited to, standard Einstein's theory - can be given a purely thermodynamic interpretation. In this approach gravity appears as an emergent phenomenon, like e.g., gas or fluid dynamics. I ...
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le (1h4m15s)

QUASARS : DES PHARES DANS LE NOIR

Les quasars sont des sources extrêmement lumineuses que l'on arrive à détecter à des distances cosmologiques. Ceux-ci peuvent servir de phares pour détecter la matière aux confins de l'Univers, interposée entre les quasars et nous, du milieu intergalactique jusqu'au sein de galaxies. Après une présentation de cette technique d'observation un peu particulière, je présenterai différentes avancées dans ce domaine et quelques-uns des défis qui nous attendent dans les années à venir.
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Conférences

le (1h33m24s)

LES DUNES QUI CHANTENT, UN NOUVEAU MODE D'ÉMISSION SONORE

Depuis Marco Polo, on sait que certaines dunes ont la particularité d'émettre des sons intenses, soit harmonieux comme des voix, soit plus irréguliers comme le fracas des armes ou, comme on le dirait maintenant, à un bombardier. Mais ces sons qui ne se produisent pas partout, sont aussi capricieux, et ne se produisent pas en permanence,  ce qui a longtemps conservé à ce phénomène un caractère mystérieux.Après avoir trouvé des dunes qui chantent aisément et remarquablement  bien, on a pu montrer  que ce son soutenu ...
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