Episodes
The search for exo-planets is currently one of the most exiting and active topics in astronomy. Small and rocky planets are particularly the subject of intense research, since if they are suitably located from their host star, they may be warm and potentially habitable worlds. On the other hand, the discovery of giant planets in short-period orbits provides important constraints on models that describe planet formation and orbital migration theories. Several projects are dedicated to discover...
Published 02/10/14
Das Gebiet der Nichtgleichgewichtsdynamik stark korrelierter Quantensysteme beinhaltet eine Vielzahl interessanter Fragestellungen, erweist sich dabei allerdings oftmals als schwer zugänglich für gängige numerische und analytische mathematische Methoden. In den letzten Jahren hat sich durch die experimentelle Realisierung gut kontrollierbarer quantenmechanischer Systeme die Möglichkeit eröffnet, Experimente als Quantensimulatoren für das Verhalten komplexer Vielteilchensysteme zu benutzen....
Published 01/30/14
The majority of stars in the universe has formed in disc galaxies with masses similar to that of the Milky Way. Ab-initio cosmological hydrodynamical simulations of the formation and evolution of galaxies in a Lambda Cold Dark Matter universe have long suffered from serious problems in correctly modelling the star-formation history and structure of disc galaxies. We first use idealized semi-cosmological simulations to gain a better understanding of processes leading to problems in disc...
Published 01/29/14
Semiconducting single-walled carbon nanotubes (CNTs) exhibit a chirality depended band structure of a one-dimensional lattice. Due to the radiative recombination of excitons CNTs emit photoluminescence in the near and mid infrared ranges depending on the tube diameter. Excitons are subject to diffusion along the tube before radiative recombination. Thereby they probe sites that give rise to spin-flips or non-radiative decay, or, at cryogenic temperatures, they localize in zero-dimensional...
Published 01/27/14
Diese Doktorarbeit umfasst zwei getrennte Analysen: zum einen die Messung des Verzweigungsverhaeltnisses B0 -> Psi(2S)Pi0 aus den Daten des Belle Experimentes, zum anderen die Abschaetzung der Rate von QED Untergrundereignissen bei kleinen Impulsen fuer das Detektorupgrade Belle II und deren Einfluss auf das Leistungsverhalten des neuen Pixeldetektors. In der ersten Analyse wurde der Zerfallskanal B0 -> Psi(2S)Pi0 untersucht und zum ersten Mal das zugehoerige Verzweigungsverhaeltnis...
Published 01/24/14
Published 01/08/14
Published 12/18/13
Durch moderne Laserspektroskopie ist es mittlerweile möglich, chemische Reaktionen mit einer Zeitauflösung von wenigen Femtosekunden zu untersuchen. Auf der anderen Seite kann die Molekülstruktur mithilfe von Röntgenstrukturanalyse sehr exakt bestimmt werden. Die vorliegende Doktorarbeit beschäftigt sich damit, diese beiden Gebiete zusammenzubringen. Der erste Teil der Dissertation beschreibt den Aufbau einer Laserplasmaquelle am Lehrstuhl für BioMolekulare Optik. Ein hochenergetischer...
Published 12/17/13
The Carina Nebula Complex is known to be an active star-formation region. This work presents a large catalogue of point-like sources assembled from archive data of the Infrared Array Camera (IRAC) onboard the Spitzer Space Telescope. This catalogue covers a region of 2.3 deg × 3.0 deg, which makes it the most extendended mid-infrared survey undertaken of the Carina Nebula Complex to date. From the catalogue a subsample of candidate young stellar objects is extracted utilising the fact that...
Published 12/12/13
The morphological analysis of galaxy clusters in X-rays allows a reliable determination of their dynamical state. Substructures on (sub-)Mpc scale influence the gravitational potential of a cluster and manifest themselves in the X-ray surface brightness distribution as secondary peaks or overall irregular shape. They lead to deviations from the hydrostatic equilibrium and spherical shape, two assumptions which are widely used in galaxy cluster studies to derive global astrophysical...
Published 12/09/13
Idealized numerical model experiments are presented to investigate the convective generation of vertical vorticity in a tropical depression. The calculations are motivated by observations made during the recent PREDICT field experiment to study tropical cyclogenesis, and by a desire to understand the aggregation of vorticity debris produced by deep convection in models of tropical cyclogenesis to form a monopole vortex. One aim is to isolate and quantify the effects of low to mid level dry...
Published 12/06/13