Yazar "Aydin, Hueseyin" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    Cylindrically symmetric fluid in unimodular f (R) gravity
    (Springer, 2019) Aydin, Hueseyin; Dogru, Melis Ulu
    In this paper, we examine static cylindrical symmetric fluid in unimodular f (R) gravity. Unimodularity for cylindrical symmetric spacetime geometry is ensured with a coordinate transformation by using tetrad formalism. Field equation solutions for given matter and the spacetime are obtained. Resource of cosmic matter is discussed by using Equation of State (EoS) and energy conditions. We investigate weak and strong energy conditions in unimodular f (R) gravity context with the help of Raychaudhuri equations. Obtained results show that fluids which violate the energy conditions cause the proposed unimodular and cylindrical symmetric wormholes, but this kind of wormholes do not satisfy traversability conditions. Furthermore, the obtained solutions indicate that. coefficient in EoS must have the condition. = -1 for physically meaningful fluids. It is discussed whether the result is compatible with the unimodular gravitation theories.
  • [ X ]
    Öğe
    Viscous fluid with neutrino in f(R,?,X) gravity
    (Iop Publishing Ltd, 2025) Eraslan, Erkan; Dogru, Melis Ulu; Taser, Dogukan; Aydin, Hueseyin
    In this study, we investigate the Kantowski-Sachs space-time within the framework of f(R,Phi,X) gravity, incorporating a general fluid distribution with neutrino contributions. The field equations are constructed using a hybrid f(R,Phi,X) function that combines features of the Starobinsky-like model and k-essence functions with canonical scalar fields. Analytical solutions are obtained, showing that the fluid can exhibit bulk viscous behavior with neutrino contributions. The model's kinematical properties and energy conditions are investigated. NEC, WEC and DEC are satisfied, while SEC is violated, indicating scenarios where gravity repels matter, enabling exotic configurations. These results provide insights into the early universe's dynamics and the role of viscous fluids and neutrinos in modified gravity theories.