Download or read book Populations stellaires dans les galaxies h tes de noyaux actifs written by Julien Fremaux and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: La population stellaire des galaxies hôtes de noyau actif semble entretenir une relation étroite avec le degré d'activité du noyau. Ces galaxies étant trop éloignées pour qu'il soit possible de les résoudre en étoiles individuelles, il faut faire appel à une méthode de synthèse de population pour déterminer quels types d'étoiles les composent. La comparaison de ces populations stellaires avec celles de galaxies non-actives de même type morphologique nous permettra d'en savoir plus sur l'interaction entre la population stellaire et le noyau actif. Dans cette thèse, nous avons développé une nouvelle méthode de synthèse de population stellaire utilisant le flux reçu de la galaxie comme quantité observable à ajuster et tenant compte des continus non stellaires qui diluent le spectre galactique. Nous avons appliqué cette méthode à la galaxie MCG-6-30-15, de type Seyfert 1. Le domaine de longueur d'onde choisi, dans le proche infrarouge, est particulièrement bien adapté pour l'étude de la région interne des galaxies de Seyfert 1 car, contrairement au domaine visible, il est presque totalement dépourvu de raies d'émission provenant du noyau actif. Cependant, il est difficile de constituer une bibliothèque de spectres stellaires complète dans ce domaine de longueur d'onde, en raison d'un déficit d'observations. Or, cette bibliothèque est un constituant essentiel pour la synthèse de population stellaire. Il pourrait être possible de la compléter avec des spectres théoriques, générés à l'aide de modèles d'atmosphères stellaires, mais en comparant ces spectres à des observations dans le proche infrarouge, nous avons constaté un manque de fiabilité des raies d'absorption calculées.
Download or read book ETUDE DES POPULATIONS STELLAIRES DANS LES NOYAUX ACTIFS DE GALAXIES written by MARIA MARGARIDA GIL.. SEROTE NUNES ROOS and published by . This book was released on 1996 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: LE TRAVAIL PRESENTE ICI EST UNE ETUDE DE BASE DES PROBLEMES CONCERNANT L'ESTIMATION DE LA CONTAMINATION PAR LE RAYONNEMENT STELLAIRE DES NOYAUX ACTIFS DE GALAXIES. NOUS CHERCHONS QUELS TYPES D'ETOILES SONT PRESENTS DANS DES GALAXIES DE DIFFERENTS TYPES D'ACTIVITE : GALAXIES NORMALES, GALAXIES A FLAMBEE D'ETOILES, LINERS, GALAXIES DE SEYFERTS DE TYPE 2 ET 1. NOUS OBSERVONS DES GRADIENTS DE POPULATION ENTRE LES NOYAUX ET LES REGIONS CIRCUMNUCLEAIRES DANS LE BULBE DES GALAXIES SPIRALES, MAIS PAS DANS LES REGIONS CENTRALES DES ELLIPTIQUES. L'ABONDANCE EN METAUX EST GENERALEMENT ELEVEE. CET ENRICHISSEMENT EN METAUX EST LA PREUVE D'UNE INTENSE FORMATION STELLAIRE DANS LE PASSE. DES GRANDES QUANTITES DE POUSSIERE SONT OBSERVEES DANS LES NOYAUX DES GALAXIES. IL Y A DES DIFFERENCES MARQUEES SUIVANT LES TYPES D'ACTIVITE. SEUL LES GALAXIES A FLAMBEE D'ETOILES ET NGC 1275, SEYFERT 1, QUI MONTRE DES SIGNES D'INTERACTION IMPORTANTS, ONT UNE ABONDANCE EN METAUX FAIBLE ET UNE POPULATION STELLAIRE TRES JEUNE MONTRANT LA PRESENCE D'UNE FLAMBEE D'ETOILE INTENSE. LES SEYFERTS 2 SONT EGALEMENT CARACTERISEES PAR UNE POPULATION ASSEZ JEUNE MAIS MOINS INTENSE QUE DANS LES GALAXIES A FLAMBEE D'ETOILES. NGC 3516, SEYFERT 1 TYPIQUE, PRESENTE PAR CONTRE, UNE POPULATION NORMALE DANS LES REGIONS CIRCUMNUCLEAIRES CARACTERISTIQUES DE GALAXIES DU MEME TYPE MORPHOLOGIQUE. LES LINERS ONT DES POPULATIONS EVOLUEES AVEC PEU DE FORMATION STELLAIRE RECENTE. DONC, SI DES ANOMALIES DE POPULATIONS EXISTENT, ELLES SONT TRES DIFFICILES A DETECTER, DU FAIT PEUT-ETRE QUE LA RESOLUTION SPATIALE ATTEINTE A PARTIR DU SOL N'EST PAS SUFFISANTE POUR POUVOIR TOTALEMENT ISOLER LE NOYAU DE LA GALAXIE HOTE. UNE CONCLUSION IMPORTANTE DE CETTE ETUDE EST QUE NOUS NE POUVONS PAS PRENDRE UNE POPULATION STELLAIRE MOYENNE SELON LE TYPE MORPHOLOGIQUE POUR LA SOUSTRAIRE A UN SPECTRE DE GALAXIE ACTIVE DONT ON VEUT ETUDIER LA COMPOSANTE NON STELLAIRE. EN FAIT, LA POPULATION EST TRES PARTICULIERE ET CHANGE D'UNE GALAXIE A UNE AUTRE.
Download or read book L influence de l environnement grande chelle sur les populations de galaxies flamb es d toiles et noyau actif written by Jean-Christophe Mauduit and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les galaxies à flambées d'étoiles (SBG) et à noyaux actifs (NAG) sont hôtes d'une activité bien particulière dont on ne comprend pas encore bien les causes exactes, (internes ou externes). Dans cette thèse, nous avons utilisé le 6dFGS, relevé spectroscopique de galaxies avantageusement basé sur des catalogues photométriques en proche-infrarouge (NIR) afin de mieux quantifier l'environnement de ces galaxies. Nous nous sommes majoritairement intéressés aux galaxies émettrices en continu radio par recoupement avec le relevé NVSS à 1.4 GHz. Nous nous sommes focalisés sur l'influence de l'environnement sur les SBG et NAG à l'échelle du superamas de Shapley. Nous avons pu montrer que les galaxies radio semblent éviter des régions aussi denses que le coeur du super-amas. Ceci est dû à l'état dynamique de fusion bien particulier de ses complexes d'amas. Les conditions extrêmes ont une très forte répercussion sur les galaxies, notamment sur le rapport de leur luminosité radio sur NIR (RK). Nous avons utilisé des arguments analytiques simples pour montrer que le balayage par pression de choc pourrait être accru dans des fusions d'amas, empêchant la formation d'étoiles, voir même le phénomêne NAG. Dans de telles régions, nous avons observé que les profils des galaxies d'amas dévient fortement d'un profil NFW typique. Nous avons ensuite étudié un échantillon d'amas d'Abell : nous confirmons que les amas ayant un environnement dense à grande échelle ont des profils de galaxies déviant de NFW ainsi que des RK diminués. Nous avons par la suite entrepris d'étudier la population "radio-quiet" des NAG en utilisant les spectres 6dFGS à notre disposition.
Download or read book Report written by European Southern Observatory and published by . This book was released on 1997 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Une nouvelle approche pour la synth se de populations stellaires dans les galaxies written by Eduardo Bica and published by . This book was released on 1987 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: NOUVELLE METHODE POUR LA SYNTHESE DE POPULATIONS STELLAIRES DANS LES NOYAUX DE GALAXIES UTILISANT UNE BIBLIOTHEQUE DE SPECTRES INTEGRES D'AMAS D'ETOILES. L'AVANTAGE DE CETTE METHODE PORTE SUR DEUX PARAMETRES: L'AGE ET LA METALLICITE. UNE ATTENTION SPECIALE A ETE DONNEE AUX DIFFERENTES SOURCES DE ROUGISSEMENT INTERSTELLAIRE AFFECTANT LES AMAS D'ETOILES ET LES GALAXIES. CETTE APPROCHE PERMET UNE ESTIMATION DIRECTE DE L'EVOLUTION CHIMIQUE A PARTIR DU SPECTRE EN ABSORPTION DES NOYAUX DE GALAXIES
Download or read book tude de Population Des Noyaux Actifs de Galaxie Au TeV Avec Les T lescopes H E S S Et tude de Variabilit Du Blazar PKS 2155 304 Avec Mod lisation SSC written by Jill Chevalier and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active Galactic Nuclei (AGN) have been discovered more than 50 years ago and yet they remain mysterious. Although we are sure they are powered by a supermassive black hole fed by an accretion disk and that they sometimes display a relativistic jet, the links between the black hole, the disk and the jet along with the acceleration and emission mechanisms are still unclear. Leptonic and hadronic models managing both in explaining the spectral energy distribution (SED) of blazars at high energy (in the GeV-TeV range), there is a degeneracy. However, blazars are known to be highly variable in all wavelengths. This variability can trace the mechanisms at play in the central engine and in the jet, giving a tool to discriminated between different processes.Gamma-ray astronomy started in the 60s to probe the high energy universe and find the origin of the cosmic-ray radiation. Several high energy sources were discovered and AGN were classified as the most energetic ones.The advent of the third generation of Imaging Atmospheric Cherenkov Telescopes (IACT), including the H.E.S.S. experiment, help gathering more data at very high energy (VHE) in order to understand better these objects. Space-based telescope like the Fermi-LAT, looking at gamma-rays in the GeV range, are used as well to cover all the high energy range of the emission. High energy data are of great importance because this is where the degeneracy between models appears and data are needed to build long term light curves.This thesis presents different projects I worked on during these three years. Each of them aims to have a better understanding of the blazars. For this I used two different approaches. The first one was doing population studies at TeV with the H.E.S.S. telescopes, either by looking at all the TeV sky observed by H.E.S.S. with the HEGS project or by trying to detect new objects, rare at TeV, to probe what we call the blazar sequence. The second approach was the detailed variability analysis of one particular blazar. The long term multi-wavelength variability study of the blazar PKS 2155-304 revealed an interesting behaviour, allowing to probe up to the accretion mechanism. The time series analysis methods developed for this study can be used in a more systematic way for population studies with a variability perspective rather than the SED one.
Download or read book La polarisation des noyaux actifs de galaxies written by Frédéric Marin and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Populations stellaires des galaxies actives de type Seyfert 2 written by Benoît Joguet and published by . This book was released on 2001 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1980 with total page 1242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Information Bulletin written by and published by . This book was released on 1981 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Report written by European Southern Observatory and published by . This book was released on 1996 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantum Mechanics Volume 3 written by Claude Cohen-Tannoudji and published by John Wiley & Sons. This book was released on 2019-12-16 with total page 790 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new, third volume of Cohen-Tannoudji's groundbreaking textbook covers advanced topics of quantum mechanics such as uncorrelated and correlated identical particles, the quantum theory of the electromagnetic field, absorption, emission and scattering of photons by atoms, and quantum entanglement. Written in a didactically unrivalled manner, the textbook explains the fundamental concepts in seven chapters which are elaborated in accompanying complements that provide more detailed discussions, examples and applications. * Completing the success story: the third and final volume of the quantum mechanics textbook written by 1997 Nobel laureate Claude Cohen-Tannoudji and his colleagues Bernard Diu and Franck Laloë * As easily comprehensible as possible: all steps of the physical background and its mathematical representation are spelled out explicitly * Comprehensive: in addition to the fundamentals themselves, the books comes with a wealth of elaborately explained examples and applications Claude Cohen-Tannoudji was a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris where he also studied and received his PhD in 1962. In 1973 he became Professor of atomic and molecular physics at the Collège des France. His main research interests were optical pumping, quantum optics and atom-photon interactions. In 1997, Claude Cohen-Tannoudji, together with Steven Chu and William D. Phillips, was awarded the Nobel Prize in Physics for his research on laser cooling and trapping of neutral atoms. Bernard Diu was Professor at the Denis Diderot University (Paris VII). He was engaged in research at the Laboratory of Theoretical Physics and High Energy where his focus was on strong interactions physics and statistical mechanics. Franck Laloë was a researcher at the Kastler-Brossel laboratory of the Ecole Normale Supérieure in Paris. His first assignment was with the University of Paris VI before he was appointed to the CNRS, the French National Research Center. His research was focused on optical pumping, statistical mechanics of quantum gases, musical acoustics and the foundations of quantum mechanics.
Download or read book The X ray Universe written by Wallace H. Tucker and published by . This book was released on 1985 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beyond the range of optical perception--and of ordinary imaginings--a new and violent universe lay undetected until the advent of space exploration. Supernovae, black holes, quasars and pulsars--these were the secrets of the highenergy world revealed when, for the first time, astronomers attached their instruments to rockets and lofted them beyond the earth's x-ray-absorbing atmosphere. The X-Ray Universe is the story of these explorations and the fantastic new science they brought into being. It is a first-hand account: Riccardo Giacconi is one of the principal pioneers of the field, and Wallace Tucker is a theorist who worked closely with him at many critical periods. The book carries the reader from the early days of the Naval Research Laboratory through the era of V-2 rocketry, Sputnik, and the birth of NASA, to the launching of the Einstein X-Ray Observatory. But this is by no means just a history. Behind the suspenseful, sometimes humorous details of human personality grappling with high technology lies a sophisticated exposition of current cosmology and astrophysics, from the rise and fall of the steady-state theory to the search for the missing mass of the universe.
Download or read book A New Astronomy written by David Peck Todd and published by . This book was released on 1906 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Story of Crass written by George Berger and published by . This book was released on 2009 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: In-depth interviews with the main movers in the punk rock movement--Crass members Penny Rimbaud, Gee Vaucher, and Steve Ignorant--detail the face of the revolution founded by these radical thinkers and artists. When punk ruled the waves, Crass waived the rules by putting out their own records, films, and magazines and setting up a series of situationist pranks that were dutifully covered by the world's press. Not just another iconoclastic band, Crass was a musical, social, and political phenomenon: commune dwellers that were rarely photographed and remained contemptuous of conventional pop stardom. As detailed in this history, their members explored and finally exhausted the possibilities of punk-led anarchy. This definitive biography of the band not only gives backstage access to their lives, philosophies, and the movement that followed, but also to never-before-seen photographs and rare dialogues.
Download or read book A Treatise on Astronomy written by John Frederick William Herschel and published by . This book was released on 1834 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
