Aspects énergétiques des oscillations de type solaire;
du Soleil aux étoiles
Kevin Belkacem (AGO, Liège)

Les oscillations de type solaire sont observées depuis près de quarante ans dans le Soleil et depuis plus d'une dizaine d'années dans quelques étoiles proches. L'avènement de l'astérosismologie spatiale, avec CoRoT mais aussi Kepler, permet depuis peu d'observer une myriade d'étoiles pulsant sur de tels modes. Ces oscillations sont maintenant détectées aussi bien dans les étoiles de séquence principale, les géantes rouges, mais également depuis peu dans une étoile massive.
Les couches supérieures des régions convectives sont le lieu de mouvements turbulents vigoureux. Ces mouvements turbulents génèrent des fluctuations de pressions dont une faible partie va, par un processus stochastique, exciter les modes propres de la cavité stellaire. L'amplitude de ces modes stochastiquement excités résulte d'un équilibre entre excitation et amortissement. La modélisation de ces deux mécanismes nous renseigne alors sur les propriétés dynamiques de la convection turbulente dans les étoiles.
Je présenterai les fondements théoriques de l'excitation et l'amortissement des modes de type solaire, ainsi que des comparaisons aux observations héliosismiques. J'évoquerai ensuite comment il est possible de faire de l'astérosismologie à l'aide des amplitudes, et non plus seulement des fréquences, et je montrerai comment les derniers résultats de la mission CoRoT permettent et permettront de contraindre les processus dynamiques dans les étoiles.

3D dynamical models of colliding winds in massive star binary systems
Ross Parkin (AGO, Liège)

Massive stars possess powerful stellar winds. Wind-wind collision in a massive star binary system generates a region of thermalized plasma which may emit prolifically at X-ray wavelengths. Despite significant developments in computer power 3D hydrodynamical models of the wind-wind collision in massive star binary systems remains computationally expensive and time demanding. To alleviate this problem a fast and accurate hybrid method has been developed which allows the dynamics of the system to be explored across large spatial scales. The model has been applied to the collision between the wind from the enigmatic super-massive star Eta Carinae and its mysterious companion. A parameter space exploration allows constraints to be placed on the orientation of the binary system on the plane of the sky. Further investigation also reveals tantalizing evidence for the importance of the radiation fields of the stars in explaining the behaviour of the observed X-ray emission.

Nucleon Electromagnetic Form Factors: A Short Review
Cédric Lorcé (University of Mainz)

Nucleon electromagnetic form factors have been measured and studied for many decades since they contain very rich and important informations about the nucleon structure. We propose a short review of recent experimental and theoretical progress. We will discuss in more details the current puzzle about GE/GM and the physical interpretation of form factors.

Utilisation d'analogues simples pour l'évaluation des caractéristiques de la ventilation de l'océan global - le modèle de l'entonnoir fuyant.
Anne Mouchet (AGO, Liège)

L'océan est un acteur essentiel pour la régulation du climat par le contrôle qu'exerce la circulation à grande échelle sur les taux d'échange de chaleur et de dioxyde de carbone entre celui-ci et l'atmosphère. Dans la perspective d'une meilleure compréhension du fonctionnement du climat terrestre, il apparaît nécessaire d'améliorer notre connaissance des échelles temporelles et spatiales caractérisant la ventilation des masses d'eau océaniques.

Étant donné la complexité du système océanique des informations concises peuvent difficilement être extraites des données actuellement disponibles ou des résultats fournis par les modèles de circulation générale océanique (OGCM). Un moyen permettant de contourner cette difficulté est l'utilisation d'analogues. Ces modèles simplifiés permettent généralement d'obtenir les solutions analytiques ainsi que les nombres caractéristiques de l'écoulement.

Un modèle simple de la circulation générale océanique est obtenu en considérant l'écoulement dans un tube poreux de section décroissante. Nous analysons la solution à l'état stationnaire qui permet d'obtenir des échelles caractéristiques de l'écoulement. Des simulations effectuées à l'aide d'un modèle 3D de circulation générales océanique permettent à la fois la validation de cet analogue et la calibration de ses paramètres.

Les échelles obtenues (temps de renouvellement, longueur caractéristique, diffusivité) sont en bon accord avec celles déduites par ailleurs. Une validation supplémentaire ainsi qu'une explication potentielle de l'excellent accord obtenu entre les solutions du modèle simplifié et les résultats du modèle 3D sont fournies par la fonction de distribution globale de l'âge de l'eau.

Ce modèle simplifié possède également un potentiel pour d'autres applications. Parmi celles-ci on peut citer l'évaluation des rôles respectifs de l'advection et de la diffusion dans le transport prédit par les modèles 3D sophistiqués ainsi que la possibilité d'obtenir une estimation de la diffusion numérique réelle même dans le cadre de schéma numérique complexes.

Dark Matter Direct Detection.
New solutions to the annual modulation seen by DAMA
Fu-Sin Ling (ULB)

The experiment DAMA has observed 11 successive cycles of annual modulation in the rate of nuclear recoils, with a statistical significance of 8.2 sigma. Ways to reconcile this signal with null results of other direct detection experiments lead to a low mass elastic scattering solution as well as several inelastic scattering solutions.

On the particle physics side, simple scalar extensions of the Standard Model as the Inert Doublet Model provide naturally with these possibilities and open up for interesting Grand Unified schemes.

On the astrophysics side, recent N-body simulations with baryons show that dark matter velocity distributions significantly deviate from Maxwellian ones, and suggest the existence of a dark disc component that is co-rotating with the stellar disc. It is found that the statistical significance of the DAMA solutions is strongly improved with realistic distributions.

Deducing the properties of hot nuclei from light-particle evaporation spectra
Robert Charity (Washington University, St-Louis)

Hot compound nuclei formed in fusion or more complicated reactions decay statistically. Typical decay modes are the evaporation of light particles such as neutrons, protons and alpha articles and fission. We focus on the evaporation decay modes and ask what we can learn about the properties of the hot nuclei from the kinetic spectra of these particles. In the statistical model, the evaporation decay probability is determined from the level density and the transmission coefficient or barrier penetration probabilities. We show that the transmission coefficients for hot nuclei are different to those for cold ground-state nuclei, consistent with a distribution of Coulomb barriers resulting from thermal fluctuations in the nuclear shape or density profile. The level densities show evidence for the fade out of long-range correlations associated with collection excitations with increasing excitation energy.

Maxim Yu. Khlopov (Virtual Institute of Astroparticle physics, APC laboratory, Paris 7; Centre for Cosmoparticle Physics "Cosmion" and National Research Nuclear University (Moscow Engineering Physics Institute))

Positive results of dark matter searches in DAMA/NaI and DAMA/LIBRA experiments, being put together with the results of other groups, can imply nontrivial particle physics solutions for cosmological dark matter. Stable particles with charge -2, bound with primordial helium in O-helium "atoms" (OHe), represent a specific Warmer than Cold nuclear-interacting form of dark matter. Slowed down in the terrestrial matter, OHe is elusive for direct methods of underground Dark matter detection used in cryogenic experiments. However radiative capture of OHe by Na and I nuclei can lead to annual variations of energy release in the interval of energy 2-5 keV in DAMA/NaI and DAMA/LIBRA experiments. It is shown that such energy release corresponding to OHe radiative capture in the matter of other detectors takes place for most of other experiments in a different energy ranges, making their test of DAMA results a nontrivial task.

Notez que ce séminaire sera simultanément retransmis dans l'Institut Virtuel d'Astroparticules (http://viavca.in2p3.fr/)

Marica Valentini (AGO, Liège)

ARCS (Asiago Red Clump spectroscopic Survey) is a survey completely devoted to Red Clump stars. It aims to derive accurate, multi-epoch radial velocities and atmospheric parameters of a large sample of Red Clump (RC) stars, fainter than those present in other spectroscopic surveys. 300 RC stars have been observed since now and included in the ARCS catalog.
The high intrinsic brightness and the small dispersion in absolute magnitude make the Red Clump stars a prime tracer of the structure and the kinematics of the Milky Way. In this seminar I will show some first applications of ARCS data in the kinematics of the Solar Neighborhood.

Unlocking the Mysteries of Jupiter's Aurora
Marissa Vogt (UCLA)

Auroral observations at Jupiter have played a key role in developing global magnetic field models and improving our understanding of magnetospheric dynamics. However, some fundamental questions about the Jovian polar aurora remain, such as "How much of the polar cap is open to the solar wind?" and "Where do the polar aurora regions map within (or outside) the magnetosphere?"

In this talk we will attempt to answer these questions by discussing the result we obtain by mapping auroral features to their magnetospheric sources. First we will present an overview of the available Jovian auroral observations. We will introduce the key features of the Jovian aurora, discuss the processes that drive the aurora at Jupiter, and make comparisons with the Earth. We will discuss the method we use for our mapping, in which we assume that the magnetic flux through the ionosphere must equal the magnetic flux through equator. Finally, we will compare our results to the auroral observations and discuss what they mean.

Phenomenological Aspects of Neutrino Mass Generation
Diego Aristizabal (IFPA, AGO, ULg)

Neutrino experimental data have firmly established that neutrinos have non-zero masses and mixing angles among the different generations. Given that neutrinos are massless in the Standard Model these experimental results are a striking signal of beyond Standard Model physics. In this talk I will discuss different mechanisms for neutrino mass generation emphasizing on possible phenomenological implications. In particular, I will show how the problem of neutrino mass generation may be related with the baryon asymmetry puzzle via leptogenesis.

Active Galaxies and Statistics of their Properties
Areg Mickaelian (Byurakan Astrophysical Observatory, Armenia)

Searches and studies of active galaxies are one of the most popular research subjects in the Byurakan Observatory. Markarian, Arakelian, and Kazarian galaxies are well-known, as well as a large number of bright active galaxies have been discovered among the First Byurakan Survey (FBS) blue stellar objects, by optical identification of IR and X-ray sources, and comparative analysis of multiwavelength data of extragalactic sources. 28 sources having the highest IR/opt flux ratio (sometimes reaching a few thousands) have been revealed. Their Spitzer IRS spectra are very similar to those for classical ULIRGs, one object being very like Mrk231. The luminosities are 43.3 < log [νL(5.5 μm)] < 46.7 erg/s encompassing the range from local ULIRGs to the most luminous sources discovered by Spitzer at z ~ 2. A statistical analysis of the catalog of AGN shows significant inhomogeneity, as well as incompleteness for the bright AGN. An attempt has been performed to homogenize the data and study the statistical properties of active galaxies. An overview of classifications emphasizes their historical nature and a need for numerical definition of activity.

Emissions aurorales et ionosphères de Vénus et de Mars
Cédric Cox (LPAP, AGO)

A l'inverse de la Terre et des planètes géantes, Vénus et Mars ne possèdent pas de champ magnétique intrinsèque. L'activité magnétique de Mars se limite à son champ rémanent, imprimé dans la calotte rocheuse formant sa surface. Celle de Vénus est encore plus faible. Néanmoins, des émissions aurorales ont été observées du coté nuit des deux planètes grâce aux missions Pioneer Venus et Mars Express.

Dans cette présentation, je m'exercerai à une brève revue des magnétosphères dites "induites" de Vénus et de Mars, de leur composition ionosphérique, ainsi que de la caractérisation de leurs aurores.

Integral Field Spectroscopy: Il buono, il brutto, il cattivo
Katrina Exter (KU Leuven)

I will give a general talk about Integral Field Spectroscopy: The good, the bad and the ugly. What is the technique; what instruments are there (ground and space); what science do they do; what are their good point and their bad points ?

Flux d'ozone et écologie forestière ou agricole
Observations sur des milieux différents et leur interprétation
Stanislaw Cieslik (Commission européenne - Centre commun de recherche - Ispra, Italie)

L’intérêt pour les flux d’ozone découle de son importante phytotoxicité, qui provoque notamment un ralentissement, variable suivant les espèces, de la croissance des plantes et donc de la séquestration du carbone. Les flux d’ozone au-dessus d’un couvert végétal peuvent être mesurés directement par la méthode des covariances. Cependant, la connaissance du flux au-dessus du couvert est insuffisante pour prévoir les effets physiologiques de l’ozone sur les tissus, l’ozone pénétrant dans ceux-ci au travers des stomates. Il convient donc de déterminer les flux stomataux d’ozone, ce qui ne peut s’effectuer de manière indirecte en l’absence de technique de mesure.

L’exposé sera consacré aux résultats de campagnes de mesures effectuées depuis 1992 jusqu’à ce jour au-dessus de couverts végétaux différents (forêts, cultures) par l’équipe du Centre Commun de Recherche d’Ispra, ainsi qu’à la description de l’algorithme conduisant à la détermination des flux stomataux d’ozone. L’aspect législatif (directives européennes, conventions internationales sur la protection de l’environnement) sera également abordé.

The Case for Axion Dark Matter
Pierre Sikivie (University of Florida)

Dark matter axions form a rethermalizing Bose-Einstein condensate. This provides an opportunity to distinguish axions from other forms of dark matter on observational grounds. I show that if the dark matter is axions, tidal torque theory predicts a specific structure for the phase space distribution of the halos of isolated disk galaxies, such as the Milky Way. This phase space structure is precisely that of the caustic ring model, for which observational support had been found earlier. The other dark matter candidates predict a different phase space structure for galactic halos.

Multifragmentation of nuclei and stellar matter in supernova explosions
Alexander Botvina (INR, Moscow)

Nuclear multifragmentation is a universal phenomenon occurring when a large amount of energy is deposited in a nucleus. As was established during the 25-year intensive research, multifragmentation dominates at high excitation energy (more than 3 MeV per nucleon), whereas the well-known compound-nucleus decay processes (sequential evaporation and fission) disappear gradually. Multifragmentation is responsible for as much as 10-15% of the total cross section in high energy hadron-nucleus collisions, and nearly twice more in nucleus-nucleus collisions. In the talk I give a short review of these investigations and demonstrate their practical importance for many applications. On the other hand, multifragmentation is a unique reaction for studying nuclear matter at subnuclear densities, in the coexistence region of the nuclear liquid- gas phase diagram. This region is crucial during the collapse of massive stars, subsequent supernova II explosions, and it is usual for crust of neutron stars. The statistical multifragmentation model (SMM), which was successfully used for description of multifragmentation reactions, has been generalized for astrophysical conditions. It is demonstrated that the properties of hot nuclei (in particular, their symmetry energy) extracted from multifragmentation data can essentially influence nuclear composition of stellar matter. Effects of the modified symmetry energy on weak processes (electron capture) and on nucleosynthesis are discussed.

Petite revue des résultats de Corot en matière de sismologie stellaire
F. Baudin (Institut d'Astrophysique Spatiale, Université Paris-Sud)

La photométrie de précision apportée par la mission Corot permet à la fois de détecter les transits d'éventuelles exo-planètes devant leur étoile mais aussi de suivre la variabilité de ces étoiles. Cette variabilité est souvent le fait d'oscillations globales de l'étoile qui renseignent sur l'intérieur de l'étoile. Corot a confirmé l'existence d'oscillations de type solaire dans nombre d'étoiles de la séquence principale toute comme dans des étoiles plus évoluées, ce qui était moins attendu. Cette précision photométrique, ainsi que la stabilité de l'instrument a aussi permis des premières: détection d'oscillations de type solaire dans des étoiles chaudes, lien entre oscillations et comportement éruptif d'étoiles Be. D'autres types d'oscillateurs ont pu aussi être scrutés bien plus en détail: delta Scuti, RR Lyrae, amenant aussi leur lot de questions. Le cas de la variabilité ayant d'autres origines que les oscillations globales de l'étoile sera aussi abordée avec les enseignements que l'on peut en tirer.

Formation et évolution de systèmes extrasolaires fortement non-coplanaires
Anne-Sophie Libert (FUNDP Namur)

La découverte d'une quarantaine de systèmes extrasolaires multiples aux caractéristiques orbitales étonnamment différentes de celles du Système Solaire a suscité de nouvelles questions quant à la formation et à l'évolution des systèmes planétaires. D'un point de vue dynamique, les excentricités généralement importantes des exoplanètes rendent inapproprié le cadre théorique bien développé pour l'étude du Système Solaire et nécessitent la mise en oeuvre de nouvelles études. Cet exposé illustre en particulier le rôle important de la résonance de Kozai sur la stabilité à long terme des systèmes planétaires fortement non-coplanaires, à un point tel que nous examinerons la possibilité pour différents systèmes extrasolaires actuellement détectés d'être situés dans cette zone de résonance. Nous établirons ainsi qu'un nombre significatif d'entre eux (Ups And, HD 12661, HD 19830, HD 74156) possèdent des paramètres physiques et orbitaux compatibles avec la résonance de Kozai. Concernant la question de la formation de systèmes planétaires fortement non-coplanaires, quelques mécanismes physiques pouvant générer de tels systèmes seront finalement considérés: pour un système coplanaire en migration de Type II dans un disque de gaz, nous montrerons qu'une capture en résonance en moyen mouvement lors de cette migration peut être à l'origine d'une augmentation importante de l'inclinaison mutuelle du système.

Cosmic rays and relativistic shock acceleration
Athina Meli (Erlangen Center for Astroparticle Physics, Friedrich-Alexander Universitaet Erlangen-Nuremberg)

The diffusive shock acceleration mechanism is invoked to explain non-thermal cosmic rays in Supernova Remnants, Active Galactic Nuclei Jets and Gamma-ray Bursts. Especially, the importance of achieving the highest observed cosmic ray energies by such a mechanism in a given astrophysical environment is a recurring theme. In this seminar Monte Carlo simulation studies of cosmic ray acceleration in relativistic subluminal and superluminal shocks will be presented, with an emphasis on the acquired diffuse cosmic ray signal at the highest energies observed, and the role of the efficiency of various classes of relativistic shocks will be discussed.

Alvaro Calle Cordon (University of Granada, Spain)

We use renormalization to extract universal features of the NN interaction. In the first part of this talk we shall analyze the chiral quark model for the NN interaction. We will see how while fine tuning conditions make difficult to fit NN data in these models, the introduction of suitable renormalization conditions supresses the short distance sensitivity.

Moreover, the One Boson Exchange (OBE) model using the 1/Nc expansion of QCD as a tool to keep with the predominant contributions is analyzed. We show how old nuclear Wigner SU(4) and Serber symmetries can be understood as long distance symmetries. We also address the problem of phenomenological strong form factors traditionally employed in the OBE potential. We show how invoking boundary conditions, neutron-proton phase shifts and deuteron properties become largely insensitive to the form factors and to the vector mesons.

Finally, preliminary results for the Meson Exchange Currents (MECs) are shown.

The early mass-loss of CW Leo as seen by Herschel : bow shock, thermal pulse or both ?
Djazia Ladjal (KU Leuven)

In the framework of the guaranteed time key programme 'Mass-loss of Evolved StarS' (MESS), Herschel PACS and SPIRE images have been obtained over a 30'x30' area around the well-known carbon star CW Leo (IRC +10 216). An extended structure is found in an incomplete arc of ~22' diameter, which is cospatial with the termination shock due to interaction with the interstellar medium (ISM) as defined by Sahai & Chronopoulos (2010) from ultraviolet GALEX images. The nature and the origin of the structure will be discussed during the talk. The first results obtained from analysing the images will also be presented.

Craig Roberts (Argonne National Laboratory)

Quantum Chromodynamics (QCD) is the strongly interacting part of the Standard Model of Particle Physics. It is supposed to describe the physics of pions, neutrons, protons; indeed, all hadrons. Hadron physics is unique at the cutting edge of modern science because Nature has provided us with just one instance of a fundamental strongly interacting theory; i.e., QCD. The community of science has never before confronted such a challenge as solving this theory. The physics of hadrons is dominated by two emergent phenomena: confinement; namely, the theory's elementary degrees-of-freedom have never been detected in isolation; and dynamical chiral symmetry breaking (DCSB), which is a remarkably effective mass generating mechanism that is responsible for the mass of more than 98% of visible matter in the Universe. These phenomena are not apparent in QCD’s Lagrangian, yet they play a principal role in determining Nature’s observable characteristics. I will describe how the Dyson-Schwinger equations (DSEs) of QCD: explain the origin and nature of DCSB; and have been used to elucidate some of its far-reaching consequences. The DSEs make plain that, in solving QCD, a constructive feedback between theory and extant and forthcoming experiments will most rapidly enable progress.

AGILE and Fermi satellites: latest highlights in gamma-ray astrophysics
Carlotta Pittori (AGILE Collaboration, ASI Science Data Center)

With the successful launch of the new generation gamma-ray space-based telescopes AGILE (ASI) on April 2007, and Fermi/GLAST (NASA) on June 2008, gamma-ray astrophysics entered a new era.

The study of cosmic gamma-rays in the energy range from a few tens of MeV to a few tens of GeV is only possible from space due to atmospheric absorption, and it is fundamental for our understanding of the most energetic phenomena occurring in nature.

Gamma-ray emission from cosmic sources at these energies is intrinsically non-thermal, and the study of the wide variety of gamma-ray sources, such as Galactic compact objects (black hole binaries, pulsars, SNRs, pulsar wind nebulae, etc.), Active Galactic Nuclei (AGNs), Gamma-Ray Bursts (GRBs), Terrestrial Gamma-ray Flashes (TGFs), etc. provides a unique opportunity to test theories of particle acceleration and radiation processes in extreme conditions and it may help to shed light on the foundations of physics itself.

We summarize here the recent highlights in high-energy astrophysics above 100 MeV from AGILE and Fermi missions currently operating together in space.

The XMM-LSS cluster sample and its cosmological applications
Nicolas CLERC (IRFU/SAp, Service d'Astrophysique, CE-Saclay, France)

The XMM-LSS Survey is the largest deep galaxy cluster survey to date. Extensive coverage exists from X-ray to radio wavelengths over the 11 deg2 area. The survey enables the detection of clusters (M~10^14Mo) well above redshifts z>1. Special care has been devoted to the characterization of the survey selection function and, to date, the XMM-LSS cluster sample is the only published sample of XMM serendipitous clusters with well-modelled selection criteria. We provide a tour of the XMM-LSS clusters: the topology of the 3D spatial distribution and perspectives for constraints on the density of X-ray clusters at z>1.2

La science chinoise I: La société et la philosophie
Maurice Gabriel (AGO)

Les séminaires que j'ai donnés en 2008 et 2009 tentaient de répondre à la question suivante: Pourquoi le science moderne est-elle apparue en Europe occidentale au 17e siècle? Si la réponse apportée est valable elle doit aussi permettre de comprendre pourquoi elle ne s'est pas développée dans la monde arabe ou en Chine. Nous nous proposons de le vérifier dans le cas de la Chine. Pour cela, il est nécessaire d'étudier son histoire et ses philosophes. C'est ce que nous ferons dans ce premier séminaire en insistant sur les différences avec l'Occident qui permettent de répondre à la question. Les séminaires suivants seront consacrés aux mathématiques, à l'astronomie et aux autres sciences.

Des richesses méconnues : les algorithmes d'antan et d'ailleurs
Philippe Eenens (Université de Guanajuato, Mexique)

Depuis l'Antiquité, des méthodes très ingénieuses ont été inventées pour résoudre les problèmes de calcul, non seulement en Europe mais aussi sur d'autres continents. En analysant et comparant différents algorithmes pour les quatre opérations, on constate que nous avons perdu de grandes richesses, au point de se demander si les algorithmes modernes sont vraiment les plus efficaces, tant pour l'enseignement que pour le calcul. Nous montrerons que l'algorithme optimal dépend en fait du contexte socio-économique.

Leptogenesis and CP violation in scatterings with gauge bosons
Juan Racker (University of Barcelona & ICREA)

Leptogenesis is a very attractive mechanism to explain the baryon asymmetry of the universe because it connects this mystery with the smallness of neutrino masses. In this talk we will give an introduction to leptogenesis and present new studies on the CP asymmetry generated in scatterings between the heavy neutrinos of the type I seesaw and the Standard Model gauge bosons.

L'activité cométaire dans le système solaire
Philippe Rousselot (Observatoire de Besançon)

L'activité cométaire des comètes est connue depuis longtemps dans le système solaire. Elle est créée par l'éjection de grains de poussière et de gaz par un noyau de glace soumis à l'action du rayonnement solaire. De nos jours un tel phénomène a été détecté pour un nombre croissant de petits objets du système solaire, comme les Centaures ou des objets précédemment considérés comme des astéroïdes. Les différents aspects de l'activité cométaire des petits corps du système solaire seront présentés. L'exposé abordera les principales propriétés physiques des comètes ainsi que de l'activité cométaire des Centaures et d'une nouvelle classe de comètes, les comètes de la ceinture principale. Le cas particulier du sursaut d'éclat de 174P/Echeclus, survenu à 13 UA du Soleil, sera montré plus en détail.

La science chinoise (II): Les mathématiques chinoises
Maurice Gabriel (AGO)

Nous nous limiterons à la période antérieure à l’arrivée des Européens en Chine, soit avant le 17e siècle. Les Chinois ont développé des mathématiques très différentes des nôtres car ils les pratiquaient dans un but différent. Sous certains aspects, elles étaient supérieures à celles qui eurent longtemps cours en Occident, sous d’autres, elles étaient inférieures. Par exemple, ils n’ont pas développé la géométrie euclidienne et celle qu’ils ont pratiquée était nettement moins développée. Aussi, ils ont prêté peu d’attention aux angles des triangles et de ce fait ils n’ont connu la trigonométrie qu’assez tardivement, sous l’influence indienne. Du côté positif, ils ont utilisé des méthodes de calcul basées sur l’utilisation de la « table à calculer » qui étaient bien supérieures aux nôtres (mais pas à celles des Indiens). Cela les a conduits à développer la méthode des pivots pour triangulariser des matrices, la méthode de Ruffini-Horner pour la recherche des racines des polynômes, des méthodes numériques d’interpolations allant jusqu’au 3e ordre ainsi que l’algèbre des polynômes allant jusqu’à la résolution de systèmes non-linéaires à 4 inconnues. Ces divers points seront abordés dans ce séminaire.

Spin effects in diffractive charmonia production
Roman Pasechnik (Uppsala University, Sweden)

We consider exclusive double diffractive production of scalar chi_c(0+), axial-vector chi_c(1+) and tensor chi_c(2+) charmonia in proton-(anti)proton collisions at different energies. The corresponding amplitudes for these processes are derived within the k_t-factorisation approach and the corresponding cross section is calculated with different unintegrated gluon distribution functions (UGDFs) known from the literature. We compare exclusive production of all charmonium states chi_c(0+), chi_c(1+) and chi_c(2+) including branching fraction for radiative J/Psi+gamma decay channel. Contributions from different spin states of axial-vector and tensor charmonia are quantified. Corresponding experimental consequences are discussed.

Diffraction at the H1 experiment
Richard Polifka (Charles University in Prague and DESY)

In my talk I will cover the topic of diffractive measurements in ep interactions at the HERA collider. I will briefly describe the ep collisions, the specific experimental setup and methods of reconstruction of the diffractive events. The latest results will be presented, the last part will emphasize the diffractive jet production as a tool for testing the QCD evolution.

Chemical evolution of high-mass stars in close binary systems
Kresimir Pavlovski (Keele University, Astrophysics Group and University of Zagreb, Department of Physics)

The complexity of composite spectra of close binaries makes the study of the individual component spectra extremely difficult. For this reason there exists very little information on the chemical composition of high-mass stars in close binaries, despite the importance of this for understanding the evolution of massive stars and of close binary systems. A way round this problem exists: spectral disentangling allows a time-series of composite spectra to be decomposed into their individual components. The results of an ongoing project to obtain the atmospheric parameters and the elemental abundances of high-mass components in binary systems using spectral disentangling would be presented. Comparison would be made to observational properties of single OB stars, and to theoretical predictions of rotational evolutionary models.

Neutrino oscillations within a quantum field theory of relatistic wave packets
Dmitry V. Naumov (JINR, Russia)

I will briefly review the current status of neutrino oscillations: neutrino masses and mixing angles, recent experimental results and some future projects. Some difficulties and paradoxes of the conventional quantum-mechanical theory of neutrino oscillations will be discussed further to request a more general approach free of these problems. As a possible approach I will discuss in some details a theory of neutrino oscillations within the S-matrix formalism of QFT with relativistic wave packets describing initial and final states and a virtual neutrino propagating through a macroscopic distance. The effect of "neutrino oscillations" appears just due to an interference of Feynman diagrams with neutrinos of different masses in the intermediate states. We perform the calculations up to the number of events seen by a detector to identify a dimensionless factor responsible for the flavor transition. The conditions are analyzed under which the last factor can be treated as the flavor transition probability in the usual quantum mechanical sense, while our formula in generally differs by additional suppression factors. It turned out that the developed theory is general enough to address also the question if the charged leptons can oscillate and what are the conditions for quantum coherence of states.

Coronae and wind-shocks - intermediate mass stars in X-rays
Jan Robrade (Hamburger Sternwarte, Germany)

I will present results from our works on the hottest magnetically active stars like Altair and show interesting new X-ray data from our current investigation of the coolest wind-shock stars. The discussed objects are mainly A-type stars (including magnetic Ap-stars) and bridge the cool and hot star community. In this regime, the typical X-ray emitting processes are magnetic activity/coronae in mid/late A-type stars and magnetically channeled wind-shocks (MCWS) in early A-type stars.

Three-body final states in dark matter annihilations and decays
Carlos Yaguna (Instituto de Fisica Teorica UAM/CSIC, Madrid)

In dark matter studies, the annihilation rate of dark matter particles plays a crucial role, for it determines their relic density and their indirect detection signal. I will show that this annihilation (or decay) rate can receive large additional contributions from three-body final states consisting of a real and a virtual massive particle, such as WW* (Wff') and tt* (tWb). As a result of these previously neglected processes, the viable parameter space of dark matter models is modified and the predictions for the direct and the indirect detection of dark matter are significantly altered. I will illustrate the relevance of these effects in supersymmetric and non-supersymetric scenarios.

The nature of dark matter
Peter Biermann (MPI for Radioastronomy, Bonn, Germany)

Dark matter has been detected since 1933 (Zwicky) and basically behaves like a non- EM-interacting gravitational gas of particles. From particle physics Supersymmetry suggests with an elegant argument that there should be a lightest supersymmetric particle, which is a dark matter candidate, possibly visible via decay in odd properties of energetic particles and photons: Observations have discovered: i) an upturn in the CR-positron fraction (Pamela: Adriani et al. 2009 Nature), ii) an upturn in the CR-electron spectrum (ATIC: Chang et al. 2008 Nature; Fermi: Aharonian et al. 2009 AA), iii) a flat radio emission component near the Galactic Center (WMAP haze: Dobler & Finkbeiner 2008 ApJ), iv) a corresponding IC component in gamma rays (Fermi haze: Dobler et al. 2010 ApJ, Su et al. 2010 arXiv), v) the 511 keV annihilation line also near the Galactic Center (Integral: Weidenspointner et al. 2008 NewAR), and most recently, vi) an upturn in the CR-spectra of all elements from Helium (CREAM: Ahn et al. 2009 ApJ, 2010 ApJL; for H and He the upturn has been confirmed by Pamela, shown at the COSPAR meeting July 2010).

All these features can be quantitatively explained with the action of cosmic rays accelerated in the magnetic winds of very massive stars, when they explode, based on well-defined predictions from 1993. While the leptonic part of these observations may be explainable with pulsars and their winds, the hadronic part clearly needs very massive stars, such as Wolf-Rayet stars, their winds and their explosions. What the cosmic ray work shows, that allowing for the magnetic field topology of Wolf Rayet star winds, both the leptonic and the hadronic part get readily and quantitatively explained, close to what had been predicted, without any significant free parameter, so by Occam’s razor the Wolf-Rayet star wind proposal is much simpler. This allows to go back to galaxy data to derive the key properties of the dark matter particle: Work by Hogan & Dalcanton, Gilmore et al., Strigari et al., Gentile et al.; work by Boyanovsky et al., DeVega & Sanchez clearly points to a keV particle. A right-handed neutrino is a candidate to be this particle: This particle has the advantage to allow star formation very early, near redshift 80, and so also allows the formation of supermassive black holes, possibly formed out of agglomerating massive stars in the gravitational potential of a dark matter clump; the stellar wind limit derived by Yungelson et al. 2008 AA does not apply for stars at near zero heavy elements, since such stars have weak winds. Black holes in turn also merge, but in this manner start their mergers at masses of a few million solar masses; the mass is given by the instability of stars at such a mass due to General Relativity and radiation effects. This readily explains the supermassive black hole mass function as the result of mergers between black holes. The corresponding gravitational waves are not constrained by any existing limit, and could have given a substantial energy contribution at high redshift. Our conclusion is that a right-handed neutrino of a mass of a few keV is the most interesting candidate to constitute dark matter. A consequence should be Lyman alpha emission and absorption at around a few microns; corresponding emission and absorption lines might be visible from molecular Hydrogen H2 and H3 and their ions, in the far infrared and sub-mm wavelength range. The detection at very high redshift of massive star formation, stellar evolution and the formation of the first super-massive black holes would constitute the most striking and testable prediction of this specific dark matter particle proposal.

La science chinoise (III) - L’astronomie
Maurice Gabriel (AGO)

Ce troisième séminaire sera consacré à l’astronomie chinoise. Ils ont regardé le ciel avec des préjugés différents des Occidentaux ce qui les a conduit à favoriser le système de coordonnées équatoriales et à rechercher les changements dans le ciel (étoiles nouvelles, taches solaires, comètes). L’élaboration d’un calendrier (luni-solaire) et la prédiction des éclipses ainsi que de certains points remarquables des orbites planétaires étaient aussi pour eux importants. Toutefois la pauvreté de leur cosmologie et de leur géométrie leur a posé bien des problèmes. On peut aussi se poser des questions sur leurs qualités d’observateurs ; ainsi ils n’ont découvert que très tardivement la précession des équinoxes ou que le mouvement du soleil et de la lune ne se faisait pas à vitesse constante. S’ils ont précédé les Occidents dans l’élaboration de cartes du ciel construites avec précision, elles utilisaient des observations qui elles ne brillaient pas par leurs qualités. Si l’astronomie chinoise présente quelques points forts, elle souffre aussi de lourds handicaps qui ne lui aurait pas permis de contribuer, comme ce fut le cas en Occident, à la naissance de la science moderne.

Parton Distributions
Cédric Lorcé (University of Mainz)

I propose a tour in the realm of parton distributions from the phenomenological point of view. Part of the presentation will be devoted to the connection between the different parton distributions and to their physical interpretation. Some manifestations of orbital angular momentum will be discussed as well as the problem of determining its contribution to the total angular momentum of the proton. I will also present a general expression for the three-quark amplitude in constituent quark models on the light cone. This allows one to estimate within a single formalism all the parton distributions and to look for possible links between different subsets of parton distributions.

High-Energy Astronomy in ESA's Science Programme
Arvind Parmar (ESA)

ESA has played an important role in the development of high-energy astronomy since the launches of COS-B in 1975 and EXOSAT in 1983. I briefly describe what we learned from these missions before turning to ESA's current high energy missions: Integral and XMM-Newton and the wonderful science that they are producing. I discuss the possibilities for astronomers to obtain new observations from these missions and to exploit their extensive archives. Finally, I discuss the future. The future for high-energy astronomy is a global mission called IXO - for International X-ray Observatory and I present the potential of IXO to make exciting discoveries in an era which will be increasingly dominated by large, multi-national, facilities.

A review on astrophysical properties of mirror dark matter
Paolo Ciarcelluti (-)

Mirror matter is a self-collisional dark matter candidate. If exact mirror parity is a conserved symmetry of nature, there could exist a parallel hidden (mirror) sector of particles which have the same masses and physical laws of our (visible) sector (except for the handedness of weak interactions). The two sectors interact each other predominantly via gravity, therefore mirror matter is naturally "dark". This candidate is compatible with recent results of DAMA and other direct detection experiments. In addition, it provides a possible intriguing interpretation for the recent observations of masses and radii of neutron stars. The most promising way to test this dark matter candidate is to look at its astrophysical signatures, as Big Bang nucleosynthesis, primordial structure formation and evolution, cosmic microwave background and large scale structure power spectra, dark stellar structures. I review the status of research on these topics.

Pierre-Philippe MATHIEU (European Space Agency (ESRIN - EOP/SE))

Europe’s capability for monitoring of our global environment from space is rapidly expanding.

The European Space Agency (ESA) is developing a wealth of new Earth Observation (EO) missions. This includes a series of Earth Explorer missions (e.g. GOCE, SMOS, Cryosat-2 recently launched, and Swarm, ADM-Aeolus, EarthCARE) addressing specific scientific issues in global change research, the new generation of geostationary and polar Meteorological missions (e.g. MSG-2/3, MTG & EPS) in joint undertaking with EUMETSAT, as well as a family of 5 Sentinel missions responding to European policy needs within the framework of the Global Monitoring for Environment & Security (GMES) programme in partnership with the European Commission (EC).

This expanding EO capability, capitalizing on 30+ years of investment in the space sector, will ensure the continuity of long-term high-quality records of environmental and meteorological data, which have been gathered in Europe through a variety of missions, including for example Envisat (since 2002), ERS (since 1991), and the family of meteorological satellites (since 1977). These European EO missions, in full synergy with national missions, provide Europe with a very powerful tool to contribute to the monitoring of climate system at the global scale, thereby paving the way towards a new ESA programme referred as the “Climate Change Initiative” (CCI).

This presentation will describe in more details the “Climate Change Initiative” (CCI) programme (75MEUR over 6 years), which aims to “systematically generate, preserve and give access to long-term data sets of some of the Essential Climate Variables (ECVs) required to meet the needs of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC)”.

In particular, this talk will discuss the opportunities of the programme, how it can foster interactions between EO data communities and climate research communities, and provide the foundation for climate science, modelling and also climate services. Finally, it will discuss some of the specific challenges it raises for the EO community in order to generate accurate and stable long-term climate data records (e.g. issue of error characterization, validation, quality assessment) and accelerate their uptake in climate models.

Interacting dark matter-dark energy
Laura Lopez-Honorez (ULB)

Dark matter and dark energy are the two components that dominate the matter energy content of our Universe. As of today their true substance is still unknown. Dark matter and dark energy are usually considered as two independent fluids, nothing prevents though the existence of an interaction between them. In my talk, after proposing some classification of the interactions studied in the literature I will go through several possible probes of the dark coupling. I will show that an interaction in the dark sector is still allowed by present data.

La science chinoise (IV)
Maurice Gabriel (AGO)

Ce dernier séminaire passera en revue les apports de la Chine dans les autres sciences que les mathématiques et l’astronomie à savoir : la sismographie, la cartographie, la physique (mécanique, constitution de la matière, optique, acoustique et magnétisme). Finalement, nous aborderons brièvement leurs apports particulièrement nombreux dans les domaines techniques. Aussi, André Lejeune nous présentera une boussole chinoise du 18e siècle ainsi qu’un boulier compteur.

Probing the structure of quasars with microlensing
Dominique Sluse (Astronomisches Rechen-Institut am Zentrum fuer Astronomie der Universitaet Heidelberg)

Our detailed understanding of the working engine of quasars is still incomplete. Several basic questions remain such as: How is the supermassive black hole in the center of quasars fed ? What is the geometry and kinematics of the gas flow near the black hole ? The answer to these questions is still elusive, mainly because the inner regions of the quasars remain unresolved by current telescopes. However, nature provides us with gravitational lens telescopes which help us in our understanding of quasars: Multiply imaged lensed quasars, which are observed when a massive galaxy lies on our line-of-sight to a distant quasar. In these systems, the stars in the lensing galaxy magnify regions of the lensed quasar as small as a few milli-arcsecs. This scale coincides with the size of the region where most of the quasar emission originates. In this talk I will show that it is possible to use this so-called microlensing effect as a tool to probe the quasar structure. I will explain how the study of the spectral variations of quasars induced by microlensing allows us to measure the temperature profile of the accretion disk, to estimate the size and study the geometry of the region emitting the quasar broad emission lines.

Extra dimensions and the gravitation potential taking into account the nucleon form factor
Oleg Selyugin (JINR, Dubna)

We examine the impact of the KK-modes in d-brane models of gravity, with large compactification radii and TeV-scale quantum gravity, on the hadronic potential at small impact parameters. We analyse the effects of the gravitational hadron form factors obtained from the hadron generalized parton distributions (GPDs) on the behavior of the gravitational potential and obtain the scattering amplitude with the eikonal corrections. We finally discuss the possible oscillations of the scattering amplitudes in the Coulomb and gravitation interactions.