Browsing Fizik by Subject "Cosmology."

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  • Analytic solutions of scalar field cosmology with minimal and nonminimal coupling and deformed discrete and finite quantum systems 
    İldeş, Medine. (Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022)
    In this thesis first, we study analytic solutions of cosmology. We investigate the most general cosmological model with real scalar field which is minimally coupled to gravity and Brans- Dicke cosmology. Field equations ...
  • Black holes, cosmology and Brans-Dicke theories in 4+1 dimensional universe 
    Çiftci, Dilek. (Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2007., 2007.)
    We consider the embedding of 3+1 dimensional cosmology in 4+1 dimensional Jordan-Brans-Dicke theory. We show that exponentially growing and power law scale factors are implied. We solve the Brans-Dicke equations and we ...
  • Cosmology and spontaneous symmetry breaking 
    Saygılı, Kamuran. (Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1998., 1998.)
    In the first problem we investigate a model which incorporates spontaneous symmetry breaking and gravitation in the context of scalar-tensor theory. Present day value of the gravitational constant is induced by the vacuum ...
  • Dark energy problem and possible solutions 
    Çamlıbel, Ali Kazım. (Thesis (M.S.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2009., 2009.)
    The end of the twentieth century is marked by a revolutionary discovery in cosmology: The expansion of the universe is accelerating, as revealed by measurements of type Ia supernovae at z 1. This most likely means that ...
  • Gravitational wave solutions to linearized Jordan Brans Dicke theory on a cosmological background 
    Dünya, Önder. (Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2017., 2017.)
    In this thesis, approximate vacuum solutions of Jordan-Brans-Dicke theory for perturbed scalar eld and perturbed Robertson-Walker metric, were found. First we obtained solutions for the scale factor a(t) and the scalar ...
  • Kinetic theory in k=0 Friedmann-Robertson-Walker cosmology 
    Tülümen, Nimet. (Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2016., 2016.)
    In the thesis we calculated Boltzmann Equation in RW metric. After that in the at space-like slices we showed that for RW metric it is not possible to nd any equilibrium solutions. However we looked for the equilibrium ...
  • On cosmological supernova observations and alternative gravity theories 
    Feyzioğlu, Mehmet Akif. (Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2019., 2019.)
    This thesis is about getting the most information from the cosmological super nova data about the expansion history of the homogeneous and isotropic universe, with the least possible set of assumptions. To this end, we fit ...
  • On the cosmological impact of a quantized scalar field 
    Algan, Merve Tarman. (Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2015., 2016.)
    We explicitly compute the leading order contribution to the stress-energy- momentum tensor of a scalar eld, which propagates in a Friedmann-Robertson-Walker (FRW) universe and placed in the in nite adiabatic vacuum. Since ...
  • On the history of expansion and matter - energy content of the universe 
    Çamlıbel, Ali Kazım. (Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2016., 2016.)
    The aim of this dissertation is to explore the vast phenomenological area between the cosmological observations and the theoretical approaches. We are speci cally focusing on type Ia supernova data and what they tell us ...
  • Primordial and late-time inflation in Brans-Dicke cosmology 
    Çalık, Mehmet. (Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2006., 2006.)
    The basic motivation of this work is to attempt to explain the rapid primordial inflation and the observed slow late-time inflation by using the Brans-Dicke theory of gravity. We show that the ratio of primordial and ...
  • Some new cosmological applications of the energy-momentum squared gravity 
    Uzun, Nebiye Merve. (Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2021., 2021.)
    We investigate two specific forms of a new-type of modified gravity called Energy Momentum Squared Gravity (EMSG) constructed by the addition of the term f(TµνT µν) to the Einstein-Hilbert action with a cosmological constant ...

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