Search for dissertations about: "NATURVETENSKAP Fysik Astronomi och astrofysik Kosmologi"

Showing result 11 - 15 of 461 swedish dissertations containing the words NATURVETENSKAP Fysik Astronomi och astrofysik Kosmologi.

  2. 11. Arithmetic and Hyperbolic Structures in String Theory

    Author : Daniel Persson; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Instantons; Kac-Moody algebras; Spacelike singularities; String Theory;

    Abstract : 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). READ MORE

  4. 12. Cosmological Models and Singularities in General Relativity

    Author : Patrik Sandin; Claes Uggla; Alan Coley; Karlstads universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; general relativity; Bianchi cosmology; singularities; dynamical systems; Fuchsian methods; Hamiltonian methods; Theory of relativity; gravitation; Relativitetsteori; gravitation; Physics; Fysik;

    Abstract : 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. READ MORE

  5. 13. A Study of Grain Drift in C Stars : Theoretical Modeling of Dust-Driven Winds in Carbon-Rich Pulsating Giant Stars

    Author : Christer Sandin; Susanne Höfner; Bengt Gustafsson; Lee Anne Willson; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Astronomy; hydrodynamics; radiative transfer; instabilities; dust formation; stars: AGB and post-AGB; stars: mass-loss; stars: variables: general; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Theoretical Astrophysics; teoretisk astrofysik;

    Abstract : 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. READ MORE

  6. 14. A Stacked Prism Lens Concept for Next-Generation Hard X-Ray Telescopes

    Author : Wujun Mi; Mats Danielsson; Peter Nillius; Ralf K. Heilmann; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; focusing X-ray telescopes; Wolter-I optics; stacked prism lens; focused UV lithography; grayscale e-beam lithography; proximity effect correction; angular resolution; effective collecting area; röntgenteleskop; Wolter-I-optik; staplade prismalinser; fokuserad UV-litografi; elektronstråle-litografi; Fysik; Physics;

    Abstract : 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. READ MORE

  7. 15. Quasars and Low Surface Brightness Galaxies as Probes of Dark Matter

    Author : Erik Zackrisson; Nils Bergvall; Kjell Olofsson; Julianne Dalcanton; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Cosmology: dark matter; gravitational lensing; quasars: general; quasars: redshift; galaxies: halos; galaxies: formation; galaxies: stellar content; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik;

    Abstract : 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. READ MORE