Sökning: "NATURVETENSKAP Fysik Astronomi och astrofysik Kosmologi"
Visar resultat 11 - 15 av 469 avhandlingar innehållade orden NATURVETENSKAP Fysik Astronomi och astrofysik Kosmologi.
11. Arithmetic and Hyperbolic Structures in String Theory
Sammanfattning : This thesis consists of an introductory text followed by two separate parts which may be read independently of each other. In Part I we analyze certain hyperbolic structures arising when studying gravity in the vicinity of spacelike singularities (the BKL-limit). LÄS MER
12. Cosmological Models and Singularities in General Relativity
Sammanfattning : This is a thesis on general relativity. It analyzes dynamical properties of Einstein's field equations in cosmology and in the vicinity of spacetime singularities in a number of different situations. LÄS MER
13. A Study of Grain Drift in C Stars : Theoretical Modeling of Dust-Driven Winds in Carbon-Rich Pulsating Giant Stars
Sammanfattning : A major fraction of stars will pass through a short period of dramatic events in their final evolutionary stage. Low- to intermediate-mass stars, studied here, are stripped of their outer parts in a slow massive wind. This mass loss reshapes both the star and the surrounding medium. LÄS MER
14. A Stacked Prism Lens Concept for Next-Generation Hard X-Ray Telescopes
Sammanfattning : Over the past half century, the focusing X-ray telescope has played a very prominent role in X-ray astronomy at the frontier of fundamental physics. The finer angular resolution and increased effective area have enabled more and more exciting discoveries and detailed studies of the high-energy universe, including the cosmic X-ray background (CXB) radiation, black holes in active galactic nuclei (AGN), galaxy clusters, supernova remnants, and so on. LÄS MER
15. Quasars and Low Surface Brightness Galaxies as Probes of Dark Matter
Sammanfattning : Most of the matter in the Universe appears to be in some form which does not emit or absorb light. While evidence for the existence of this dark matter has accumulated over the last seventy years, its nature remains elusive. LÄS MER