Essays about: "cosmological perturbations"

Found 5 essays containing the words cosmological perturbations.

  1. 1. Vorticity and Gravitational Wave Perturbations on Cosmological Backgrounds Using the 1+1+2 Covariant Split of Spacetime

    University essay from Umeå universitet/Institutionen för fysik

    Author : Robin Törnkvist; [2018]
    Keywords : ;

    Abstract : In this thesis we consider perturbations of a perfect fluid on locally rotationally symmetrical (LRS) class II cosmological backgrounds, with a nonvanishing vorticity of the fluid on the perturbed model. The method used is based on the 1+1+2 covariant decomposition of spacetime, motivated by the assumption of anisotropic expansion, followed by a harmonic decomposition of all gauge invariant quantities. READ MORE

  3. 2. Higgs inflation

    University essay from Uppsala universitet/Teoretisk fysik

    Author : Erik Schildt; [2018]
    Keywords : inflation; Higgs inflation; nonminimal coupling; conformal transformation; Higgs cosmology; cosmology; higgs inflaton; inflaton;

    Abstract : In this project a recent model of inflation in which the Standard Model Higgs field with a nonminimal coupling to gravity takes on the role of the inflaton field is investigated. The tensor to scalar ratio, spectral index and the running of the spectral index  is calculated for a tree level analysis and compared with the Planck experiment. READ MORE

  4. 3. 3+1 Approach to Cosmological Perturbations : Deriving the First Order Scalar Perturbations of the Einstein Field Equations

    University essay from Karlstads universitet/Fakulteten för hälsa, natur- och teknikvetenskap (from 2013)

    Author : Söderkvist Vermelin Wilhelm; [2016]
    Keywords : physics; astronomy; theoretical physics; perturbation; cosmology; cosmological perturbations; 3 1 formalism; first order perturbation; perturbation theory; universe; fysik; astronomi; teoretisk fysik; störning; störningsräkning; kosmologi; kosmologiska störningar; kosmologisk störningsräkning; 3 1 formalismen; första ordningens störningar; störningsteori; universum;

    Abstract : Experimental data suggest that the universe is homogeneous and isotropic on sufficiently large scales. An exact solution of the Einstein field equations exists for a homogeneous and isotropic universe, also known as a Friedmann-Lemaître-Robertson-Walker (FLRW) universe. READ MORE

  5. 4. Density Growth in Anisotropic Cosmologies of Bianchi Type I

    University essay from Institutionen för fysik

    Author : Tomas Sverin; [2012]
    Keywords : ;

    Abstract : This work generalises earlier works on the growth of the density perturbations in Bianchi type I cosmologies filled with dust to include also the effects of pressure anda positive cosmological constant. For the analysis the 1+3 covariant split of space-time formalism is used. READ MORE

  6. 5. Cosmological Density Perturbations

    University essay from Fakulteten för teknik- och naturvetenskap

    Author : Kristoffer Hultgren; [2007]
    Keywords : Physics; Cosmology; Astronomy; Relativity; Gravitation; Fysik; Kosmologi; Astronomi; Relativitetsteori; Gravitation;

    Abstract : This thesis presents a brief review of gravitation and cosmology, and then gives an overview of the theory of cosmological perturbations; subsequently some applications are discussed, such as large-scale structure formation. Cosmological perturbations are here presented both in the Newtonian paradigm and in two di¤erent relativistic approaches. READ MORE