Zugl.: Wien, WirtschaftsUniversiẗat, Diss.

Thesis (doctoral)--Universität, Mainz, 2007. / Includes bibliographical references.

Zugl.: Hamburg, Univ., Diss., 2007 u.d.T.: Köckert, Charlotte: Christliche Kosmologie und antike Naturphilosophie

Thesis--Leyden. / In Periodical Room. Includes bibliographical references.

Gamma-ray bursts are still not fully understood events. However, their exploration could pro- vide a useful tool for a better understanding of the early Universe because they belong to the most distant and violent objects that astronomers know. This thesis tries to bring more information about a so-called group of intermediate-duration bursts claimed by different authors employing dif- ferent data samples. Firstly, duration and spectral hardness properties of bursts from the Reuven Ramaty High-Energy Solar Spectroscopic Imager are statistically analysed. The obtained results bring a suspicion that these intermediate bursts gather into a separate group. Secondly, these bursts are investigated in more detail with respect to their spectral lags, peak count rates, red- shifts, supernova observations, and so forth. Thirdly, long-duration bursts with known redshifts and with derived pseudo-redshifts detected by The Burst and Transient Source Experiment, Swift and Fermi bursts with known redshifts, are used to study the cosmological effects on the observed flux and fluence distributions.

In this work we have examined different methods of averaging in general relativity and cosmology. We developed the method based on Cartan scalars. We computed the backreaction term for a flat LTB model with a special ansatz for the radial function. We found out that it behaves as a positive cosmological constant. In the next part of this thesis we were interested in averaging inside LRS class II dust model. For this family we averaged all the Einstein equations and the resulting system generalizes the Buchert equations. We numerically worked out two concrete examples where deceleration parameter changes its sign from positive to negative. Powered by TCPDF (www.tcpdf.org)

The dissertation focuses on the texts of a religious movement known as Tianshidao (the Way of the Celestial Masters) from the 2nd to the 5th century CE. Tianshidao is presented as a multifaceted tradition that should not be reduced by a predefned essence or a teleological vision of history. Instead of reconstructing one coherent cosmology, the author interprets the texts as representing various alternative cosmologies. They are compared according to the theory of cultural bias of Mary Douglas, in terms of grid and group. Special atention is paid to the employment of the bureaucratic imagery and the representations of time which are interpreted in the context of the cultural bias and the various modes of relationship towards the institutions of Tianshidao and the state. The author also analyses the millennialist character of the movement which was noted by previous research and distinguishes between various types of millennialism. Key words Tianshidao, Daoism, Early-Medieval China, cosmology, millennialism.

We deal with cosmological perturbation theory in my work. We investigate General Theory of Relativity in Higher Dimensions in the Chapter 1. I mention GHP-formalism and algebraical classification of spacetimes. I use spinors to show that spacetimes of dimension 4 are special. I discuss also Kundt spacetimes, which are interesting for perturbation theory of black holes. I work with perturbations of FLRW ST's in GHP formalism in Chapter 2, which we want to use in Cosmological Inflation. The final part of my thesis is connected with scalar perturbations in f(R)-cosmologies, that can be used for explaining accelerated expansion in the last 5 billion years. I investigate the Universe at the scales of 150 Mpc, where I could not use the hydrodynamical approach. Thus I work with the generalization of the Landau's mechanical approach. I need quasi-static approximation for getting the potentials Φ and Ψ, since the equations are too complicated for direct integration. I plan to use the result also for numerical simulation of motions of dwarf galaxies in these potentials. Powered by TCPDF (www.tcpdf.org)

SNe Ia können als Standardkerzen verwendet werden, um den Zustandsparameter der dunklen Energie w zu messen. Nachdem viele SN Ia beobachtet wurden, wird die Genauigkeit aktueller Studien durch systematische Fehler beschränkt, wobei die Flusskalibrierung (in Wellenlänge) die dominierende Fehlerquelle ist. In dieser Arbeit wird eine Möglichkeit präsentiert, das Problem mit dem “SNIFS Calibration Apparatus” (SCALA) zu lösen oder wenigstens zu verringern. Das Ziel von SCALA ist es, dass System aus Teleskop und SNIFS mit hoher Genauigkeit zu kalibrieren und diese Kalibration auf das Standardstern-Netzwerk zu übertragen und somit die Modellabhängigkeit zu unterdrücken. SCALA erzeugt 18 nahezu parallele und kolimierte monochromatische Strahlen (mit einstellbarer Wellenlänge), die Öffnungswinkel von einem Grad haben. Die Kombination dieser Strahlen leuchtet die Bildebene des UH 88, Teleskops (Universität Hawaii 88 inch Teleskop) mit einer Genauigkeit von 1% gleichmäß ig aus. SCALA wurde im Jahr 2014 installiert und ist seit 2015 im regulären Betrieb. Im in-situ Betrieb wird einer der Strahlen ständig mit einer Photodiode überwacht, die mit einer NIST-kalibrierten Photodiode kalibriert wurde. Eine zweite so kalibrierte Photodiode wird von Strahl zu Strahl bewegt, um den Helligkeitsverlauf der anderen 17 Strahlen als Funktion der Wellenlänge zu messen. Auf diese Weise sind wir in der Lage die Ausleuchtung von SCALA mit einer Genauigkeit von besser als 1% zu vermessen. Auf diese Weise kann mit der bekannten Wellenlänge des verwendeten Lichts die Transmissionskurve des SNIFS+UH 88 Systems gemessen werden. Die gemessenen systematischen Ungenauigkeiten der Messung sind kleiner als 0.7%. Der nächste Schritt besteht darin, die mit SCALA erreichte Kalibration mit einer herkömmlichen, auf Basis des Standard Stern Netzwerkes, zu vergleichen. / SNe Ia can be used as standard candles to measure the dark energy equation of state parameter, w. Having observed a good number of these objects, current studies are limited by systematic uncertainties, among which relative (color) flux calibration is dominating. This work presents a way to solve, or at least limit, the problem with the SNIFS Calibration Apparatus (SCALA). SCALA's goal is to provide high precision calibration for the “telescope+ SNIFS” system and refine the primary standard star network, to eliminate the uncertainties due to the knowledge of their models. SCALA produces 18 quasi-parallel and collimated monochromatic (and wavelength tunable) beams with opening angles of 1 degree. The combination of these beams allows us to achieve an illumination of the focal plane of the University of Hawaii 88 inches telescope (UH 88), that is flat to within 1%. SCALA was commissioned in 2014 and fully deployed in 2015. In the in-situ set up, one of the SCALA beams is constantly monitored by a photodiode (calibrated against a NIST-calibrated photodiode), which is used as flux standard to transfer the NIST-calibration to the telescope+instrument first, and the standard star spectra afterwards. We measure the overall wavelength trend of the illumination from SCALA with a precision better than 1%, by moving another of these calibrated photodiodes from beam to beam. We can hence measure relative trasmissivity curves for each SCALA beam. Therefore, we can produce throughput curves of the SNIFS+UH 88 system. The measured systematics affecting our results sum to errors smaller than 0.7%. The next step would be to compare the calibration of the system achieved with SCALA with the traditional calibration obtained by observing standard stars.

In this work the extension of the criterion for local thermal equilibrium by Buchholz, Ojima and Roos to curved spacetime as introduced by Schlemmer is investigated. Several problems are identified and especially the instability under time evolution which was already observed by Schlemmer is inspected. An alternative approach to local thermal equilibrium in quantum field theories on curved spacetimes is presented and discussed. In the following the dynamic system of the linear field and matter perturbations in the generic model of inflation is studied in the view of ambiguity of quantisation. In the last part the compatibility of the temperature fluctuations of the cosmic microwave background radiation with local thermal equilibrium is investigated. / In dieser Arbeit wird die von Schlemmer eingeführte Erweiterung des Kriteriums für lokales thermisches Gleichgewicht in Quantenfeldtheorien von Buchholz, Ojima und Roos auf gekrümmte Raumzeiten untersucht. Dabei werden verschiedene Probleme identifiziert und insbesondere die bereits von Schlemmer gezeigte Instabilität unter Zeitentwicklung untersucht. Es wird eine alternative Herangehensweise an lokales thermisches Gleichgewicht in Quantenfeldtheorien auf gekrümmten Raumzeiten vorgestellt und deren Probleme diskutiert. Es wird dann eine Untersuchung des dynamischen Systems der linearen Feld- und Metrikstörungen im üblichen Inflationsmodell mit Blick auf Uneindeutigkeit der Quantisierung durchgeführt. Zuletzt werden die Temperaturfluktuationen der kosmischen Hintergrundstrahlung auf Kompatibilität mit lokalem thermalem Gleichgewicht überprüft.