Yazar "Pirinccioglu, Nurettin" seçeneğine göre listele

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    Differences between scalar field and scalar density field solutions
    (Canadian Science Publishing, Nrc Research Press, 2012) Pirinccioglu, Nurettin; Sert, Ilker
    Differences between scalar field and scalar density solutions are explored using a Robertson-Walker (RW) metric, and a nonrelativistic Hamiltonian is derived for a scalar density field in the post-newtonian approximation. The results are compared with those of a scalar field. The expanding universe in a RW metric and a post-newtonian solution of the Klein-Gordon equation are discussed separately.
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    Effective Hamiltonian for non-minimally coupled scalar fields
    (Springer/Plenum Publishers, 2009) Mese, Emine; Pirinccioglu, Nurettin; Acikgoz, Irfan; Binbay, Figen
    In the post Newtonian limit, a non-relativistic Hamiltonian is derived for scalar fields with quartic self-interaction and non-minimal coupling to the curvature scalar of the background spacetime. These effects are found to contribute to the non-relativistic Hamiltonian by adding nonlinearities and by modifying the gravitational Darwin term. As we discuss briefly in the text, the impact of these novel structures can be sizable in dense media like neutron star core, and can have observable signatures in phase transitions, for example.
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    f(T,R) theory of gravity
    (World Scientific Publ Co Pte Ltd, 2018) Salti, Mustafa; Korunur, Murat; Acikgoz, Irfan; Pirinccioglu, Nurettin; Binbay, Figen
    We mainly focus on the idea that the dynamics of the whole universe may be understood by making use of torsion T and curvature R at the same time. The f(T, R)-gravity can be considered as a fundamental gravitational theory describing the evolution of the universe. The model can produce the unification of the general relativity (GR), teleparallel gravity (TPG), f(R)-gravity and f(T)-gravity theories. For this purpose, the corresponding Lagrangian density is written in terms of an arbitrary function of the torsion and curvature scalars. Furthermore, we use the absence/existence puzzle of relativistic neutron stars and thermodynamical laws as constraining tools for the new proposal.
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    Holographic scalar fields in Kaluza-Klein framework
    (Springer Heidelberg, 2017) Erkan, Sevda; Pirinccioglu, Nurettin; Salti, Mustafa; Aydogdu, Oktay
    Making use of the Friedmann-Robertson-Walker (FRW) type Kaluza-Klein universe (KKU), we discuss the holographic dark energy density (HDED) in order to develop its correspondence with some scalar field descriptions such as the tachyon, quintessence, DBI-essence, dilaton and the k-essence. It is concluded that the Kaluza-Klein-type HDED proposal becomes stable throughout the history of our universe and is consistent with the current status of the universe. Next, we obtain the exact solutions of self-interacting potential and scalar field function for the selected models.
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    Moller's four-momentum of electric and magnetic black holes
    (Springer/Plenum Publishers, 2007) Binbay, Figen; Pirinccioglu, Nurettin; Salti, Mustafa; Aydogdu, Oktay
    In order to evaluate energy and momentum components associated with two different black hole models, i.e. the electric and magnetic black holes, we use the Moller energy-momentum prescriptions both in Einstein's theory of general relativity and the teleparallel gravity. We obtain the same energy and momentum distributions in both of these different gravitation theories. The energy distribution of the electric black hole depends on the mass M and the magnetic black hole energy distribution depends on the mass M and charge Q. In the process, we notice that (a) the energy obtained in teleparallel gravity is also independent of the teleparallel dimensionless coupling parameter, which means that it is valid not only in teleparallel equivalent of general relativity but also in any teleparallel model, (b) our results also sustains the importance of the energy-momentum definitions in the evaluation of the energy distribution of a given spacetime, and (c) the results obtained support the viewpoint of Lessner that the Moller energy-momentum complex is a powerful concept of energy and momentum.
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    Topological black holes and momentum four-vector
    (World Scientific Publ Co Pte Ltd, 2007) Pirinccioglu, Nurettin; Binbay, Figen; Acikgoz, Irfan; Aydogdu, Oktay
    We consider the energy momentum definition of the Moller in both general relativity and teleparallel gravity to evaluate the energy distribution (due to both matter and fields including gravitation) associated with the topological black holes with a conformally coupled scalar field. Our results show that the energy depends on the mass M and charge Q of the black holes and cosmological constant Lambda. In some special limits, the expression of the energy reduces to the energy of the well-known spacetimes. The results also support the viewpoint of Lessner that the Moller energy momentum formulation is a powerful concept of the energy momentum. Furthermore, the energy obtained in teleparallel gravity is also independent of the teleparallel dimensionless coupling constants which means that it is valid not only in the teleparallel equivalent of the general relativity but also in any teleparallel model.