Les jets sont des phénomènes d’éjection collimatée de plasma magnétisé. Ces ph́énomènes liés à l’accrétion d’un disque sur un objet central, sont relativement répandus dans l’univers : les environnement des étoiles jeunes (objets Herbig-Haro, étoiles T Tauri), des binaires X, des sursauts gamma et les noyaux actifs de galaxies... Les jets extra-galactiques sont issus des trous noirs super-massifs au centre de galaxies telles que les quasars ou les radiogalaxies. Ils sont caractérisés par leur taille, leur puissance et la vitesse du plasma.Les jets extragalactiques sont étudiés dans de ce travail de thèse, même si les outils et méthodes développés peuvent être utilisés pour les binaires X et les micro-quasars. Nous poserons en particulier les questions des mécanismes de lancement, d’accélération et de collimation de ces écoulements. Nous traiterons également de la source énergétique à l’origine de l’écoulement qui peut atteindre une puissance de l’ordre de 10^47 erg.s−1.Le liens avec l’accrétion, la proximité de la base des jets avec le trou noir central, les vitesses d’écoulement observées dans certains jets, montrent que le traitement de ces questions doit inclure les effets de la relativité générale. Nous étudierons donc des solutions de la décomposition 3+1 des équations de la magnéto-hydrodynamique en métrique de Kerr. Nous nous appliquerons au développement d’un modèle d’écoulement méridional auto-similaire avec un traitement consistant du cylindre de lumière. Ce modèle pouvant s’appliquer à la fois au jet et à l’accrétion. Nous explorons les mécanismes d’accélération et de collimation des solutions produites. Nous calculerons des solutions de l’écoulement entrant dans l’horizon et de l’écoulement sortant à l’infini incluant des termes d’injection de paires. Le rôle du mécanisme de création de paires et des processus d’extraction de l’énergie du trou noir sera exploré. / Jets are collimated ejection phenomena of magnetized plasma. These phenomena related to the accretion of a disk on a central object, are relatively common in the universe: the environment of young stars (Herbig- Haro Objects, T Tauri stars...), X-ray binaries, Gamma-ray-bursts, and active galactic nuclei... Extragalactic jets come from super-massive black holes in the center of galaxies such as quasars or radiogalaxies. They are characterized by their size, their power and velecity of the plasma.Extragalactic jets will be the subject of studies in this thesis work, although the tools and methods developed can be used for X-ray binaries and microquasars. In particular, we will ask questions about the mechanisms of launching, accelerating and collimating these flows, but also about the energy source at the origin of the flow that can reach a power in the order of 10^47erg.s−1.The links with the accretion, the proximity of the jet base to the central black hole, flow velocities observed in some jets, show that the treatment of these issues must include the effects of general relativity. We will therefore study solutions of the 3+1 decomposition of magneto-hydrodynamic equations in Kerr metric. We will apply ourselves the development of a meridional self-similar magnetized flow model with a consistent treatment of the light cylinder effect. This model can be applied to both spine jet and accretion. We explore the mechanisms of acceleration and collimation of the obtained solutions. We will calculate solutions of the incoming flow in the horizon and the outgoing flow reaching infinity including injection terms. The role of the pair creation mechanism and the processes of extracting energy from the black hole are explored.

In this thesis, we study the energy extraction from rotating black holes in anti-de Sitter (AdS) spacetime (Kerr-AdS black holes), via the Blandford-Znajek (BZ) process. The motivation is the anti-de Sitter/conformal field theory (AdS/CFT) correspondence which provides a duality between gravitational physics in asymptotically AdS spacetimes and lower dimensional boundary field theories. The BZ process operates via a force-free magnetosphere around black holes and the rotational energy of the black hole is extracted electromagnetically in the form of Poynting flux. The major part of the thesis is devoted to obtaining force-free solutions in the Kerr-AdS background, which generalize traditional BZ solutions in the asymptotically flat Kerr background. Given the solutions, we use the AdS/CFT to infer dual descriptions in terms of the boundary field theory, which hopefully will lead to a better understanding of the energy extraction for rotating black holes. / Graduate

*Graveyards are significant sites that are consciously and deliberately created. As both architecture and landscape architecture, graveyards are an intrinsic part of history that have helped define and establish architectural styles as well as address land use and associated issues.Graveyards provide some of the best and most lasting examples of art and sculpture through the ages. By examining the size, shape, ornamentation/articulation, style of carving and materials from which the stones are constructed, elements of social status and what individuals thought of the themselves are revealed. Valuable historic documentation is gleaned from graveyards in the form of genealogical information, social history, widespread diseases, wars/battles and demographics. The study of epitaphs discloses biographies of individuals and indicates what type of professions were dominant during a certain period. The religious symbolism of individual stones differentiates denominations and may lend evidence of a once-existent church or parish.*This term was traditionally used throughout the seventeenth, eighteenth and nineteenth centuries and therefore will be applied in the text where appropriate. The need to preserve graveyards is essential to humankind's understanding of the past,, people and the environment. As outdoor museums that are open to all, regardless of social or economic status, to visit and experience, graveyards are potentially one of the best educational tools for interpreting history, yet are seldom used. Graveyards must begin to be viewed as "interpretive sites" and not just as functional and emotional places for the dead. As a tangible aspect of history that contains sensitive records, the preservation of a graveyard must be carefully and innovatively handled. The stability that a cemetery presents in the ever-changing environment of a disposable society is threatened unless the site and its artifacts are properly maintained.Historic Blandford Cemetery in Petersburg, Virginia, presents itself as a significant eighteenth, nineteenth and twentieth-century graveyard/cemetery. It is the site of the 1781 Battle of Petersburg and the burial grounds for approximately 30,000 Confederate soldiers from the United States Civil War. The Old Blandford Church is the oldest church in the Petersburg area (ca. 1734-1737) and was the last of three brick churches built for Bristol Parish of Bristol, England, in colonial Virginia. The church also contains fifteen Tiffany stained-glass windows designed by Louis Comfort Tiffany.Since the historic fabric at Blandford Cemetery needs to be preserved, restored, maintained and innovatively managed to ensure its future, this study has been undertaken with the sincere hope that others will find the enthusiasm, support and encouragement to seek out, preserve and interpret old graveyards and cemeteries. / Department of Architecture