Yazar "Caglar, Halife" seçeneğine göre listele

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    Bianchi type-I Universe in f(R, T) Modified Gravity with Quark Matter and A
    (Amer Inst Physics, 2017) Caglar, Halife; Aygun, Sezgin
    In this study, we investigate homogeneous and anisotropic Bianchi type I universe in the presence of quark matter source in f (R, T) gravity (Harko et al. in Phys. Rev. D 84:024020, 2011) with cosmological constant A (where R is the Ricci scalar and T is the trace of the energy momentum tensor). For this aim we have used the anisotropy feature of Bianchi type I universe and equation of states (EoS) of quark matter. We explore the exact solution f(R, T)=R + 2f(T) model for Bianchi type I universe model. When t -> infinity, we get very small cosmological constant value, this result agrees with recent observations.
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    Energy and Momentum of Higher Dimensional Black Holes
    (Springer/Plenum Publishers, 2012) Dogru, Melis Ulu; Varlikli, Neriman; Baykal, Derya; Kiy, Guliz; Taser, Dogukan; Caglar, Halife; Gunduz, Emine
    In this paper, we devote to investigate the energy-momentum problem of higher dimensional black holes in the general theory of relativity. The energy and momentum complex of Moller has been used for the calculations. Also, total energy and total momentum of some special cases for higher dimensional black holes such as Schwarzschild-like black holes, Reissner-Nordstrom-like charged black holes, AdS-like black holes, topological black holes, BTZ-like and charged BTZ-like black holes were obtained. It is invented that the momentum of black holes vanishes everywhere while the energy of black holes are not equal to zero in higher dimension. Also the results agree with Yang and Radinschi or Vagenas results in three and four dimensional black holes, respectively (Jang and Radinschi in AIP Conf. Proc. 895, 325, 2007; Vagenas in Mod. Phys. Lett. A 21, 1947, 2006).
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    ENERGY-MOMENTUM DISTRIBUTIONS OF FIVE-DIMENSIONAL HOMOGENEOUS-ANISOTROPIC UNIVERSES
    (World Scientific Publ Co Pte Ltd, 2012) Dogru, Melis Ulu; Baykal, Derya; Kiy, Guliz; Taser, Dogukan; Caglar, Halife; Varlikli, Neriman
    In this study, it has been investigated whether the energy and momentum can be localizable for five-dimensional homogeneous and anisotropic universes. In this connection, energy and momentum of five-dimensional Bianchi type-I, type-III and type-V spacetimes have been calculated in the framework of general relativity (GR) and teleparallel gravity (TG). Einstein, Bergmann-Thomson, Landau-Lifshitz, Papapetrou, Tolman and Moller energy-momentum complexes have been used to obtain these related quantities of given the spacetimes in GR, while Einstein, Bergmann-Thomson, Landau-Lifshitz and Moller prescriptions have been used to obtain these related quantities of the spacetimes in TG. It has been found that all of the energy and momentum distributions of five-dimensional Bianchi type-I spacetime are equal to zero in GR and TG. For five-dimensional Bianchi type-III and type-V spacetimes, Bergmann-Thomson, Einstein and Tolman energy and momentum components give the same results, however Moller, Landau-Lifshitz and Papapetrou energy-momentum distributions give different results in general relativity. Also, in TG, Bergmann-Thomson and Einstein energy and momentum components give the same results for the Bianchi type-III and type-V spacetimes, too. In this sense, it is seen that Einstein, Bergmann-Thomson and Landau-Lifshitz energy and momentum descriptions of these spacetimes have been given same results in both theories, GR and TG.
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    Exact Solutions of Bulk Viscous With String Cloud Attached to Strange Quark Matter For Higher Dimensional FRW Universe in Lyra Geometry
    (Amer Inst Physics, 2016) Caglar, Halife; Aygun, Sezgin
    In this study, we have investigated bulk viscous with strange quark matter attached to the string cloud for higher dimensional Friedman-Robertson-Walker (FRW) universe in Lyra geometry. By using varying deceleration parameter and conservation equations we have solved Einstein Field Equations (EFE's) and obtained generalized exact solutions for our model. Also we have found that string is not survived for bulk viscous with strange quark matter attached to the string cloud in framework higher dimensional FRW universe in Lyra geometry. This result agrees with Kiran and Reddy, Krori et al, Sahoo and Mishra and Mohanty et al. in four and five dimensions.
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    Generalized linearly varying deceleration parameter solutions of higher dimensional universe in f(R,T) theory
    (World Scientific Publ Co Pte Ltd, 2024) Caglar, Halife
    In this paper, generalized Friedmann-Robertson-Walker universe for Strange Quark Matter (SQM) and Normal Matter (NM) coupled with Domain Wall (DW) in form perfect fluid have been investigated in f(R,T) modified theory. f(R,T) function has been assumed as f(R,T)=R+mu T and Modified Field Equations (MEFEs) have been attained. The MEFEs of the constructed model do not allow solutions of open and closed FRW universe. Obtained modified field equations of higher dimensional flat FRW universe have been solved by using Linearly Varying Deceleration Parameter (LVDP) suggested by Akarsu and Dereli [Int. J. Theor. Phys. 51, 612 (2012)]. Pressure and energy density of the matter distributions for the Linearly Expansion Model (LEM) and Constant Expansion Model (CEM) have been attained as decreasing values by the cosmic time t and constant mu in f(R,T) gravity. But for the Exponential Expansion Model (XEM), these quantities have been obtained as time-independent. It is found out that the domain wall behaves like invisible matter when s1=0 due to negative domain wall tension (sigma(LSQM)(w)=-B-c) for SQM with DW of LEM. Strange quark matters for LDW and CDW models behave like cold dark matter when s(1)=0 and s(3)=0, respectively. One can say that SQM with DW for LEM and CEM may cause the expansion of the universe in these special situations. Also, solutions of XEM have shown that domain wall matter behaves like stiff matter when mu=20 pi. All solutions of the constructed model in f(R,T) theory have been reduced to General Relativity (GR) theory solutions by assuming mu=0. Finally, all solutions obtained have been discussed in detail.
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    Higher Dimensional FRW Universe Solutions in Creation Field Cosmology
    (Amer Inst Physics, 2017) Caglar, Halife; Aygun, Sezgin
    In this study, we investigate the solutions of higher dimensional Friedmann-Robertson-Walker (FRW) universe in Creation Field Cosmology (CFC) when strange quark matter (SQM) and normal matter (NM) attached to the string cloud and domain walls. Using deceleration parameter, we get two different solutions in CFC. Also, we obtain zero string tension density (rho(s) = 0) for SQM attached to the string cloud. We get constant creation field function C for SQM and normal matter attached to domain walls. Also, the features of obtained solutions are generalized and discussed.
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    Non-existence of Brans-Dicke theory in higher dimensional FRW universe
    (Springer, 2016) Caglar, Halife; Aygun, Sezgin
    In this paper, we have studied exact solutions of Brans-Dicke (BD) theory for higher dimensional generalized Friedmann-Robertson-Walker (FRW) universe in the presence of strange quark matter (SQM) attached to the string cloud and domain walls. We have obtained that string tension density does not survive in this model. This result agrees with Kiran and Reddy, Krori et al., Sahoo and Mishra and Reddy. Also we have obtained constant scalar field in the presence of string cloud and domain walls. Then BD theory does not observe for higher dimensional FRW universe with SQM attached to the string cloud and domain walls. Our BD solutions turn into general relativity (GR). Finally, some physical properties are discussed.
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    Quadratic Equation of State Solutions for Bianchi type-V Universe Model in f (R, T) Gravity
    (Amer Inst Physics, 2019) Caglar, Halife
    In this study, f(R,T) gravitation theory has been investigated in the presence of perfect fluid matter distribution for Bianchi type V universe model with a cosmological term (A). For the solutions of the model, quadratic equation of state (EoS) parameter in the form of p = up(2) - p and anisotropy future of the universe have been used. Also, General Relativity solutions have been obtained for this model.
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    String cloud and domain walls with quark matter for a higher dimensional FRW universe in self creation cosmology
    (Chinese Physical Soc, 2016) Caglar, Halife; Aygun, Sezgin
    In this study, we research a higher dimensional flat Friedmann-Robertson-Walker (FRW) universe in Barber's second theory when strange quark matter (SQM) and normal matter (NM) are attached to the string cloud and domain walls. We obtain zero string tension density for this model. We obtain dust quark matter solutions. This result agrees with Kiran and Reddy, Krori et al, Sahoo and Mishra and Reddy. In our solutions the quark matter transforms to other particles over time. We also obtain two different solutions for domain walls with quark and normal matters by using a deceleration parameter. Also, the features of the obtained solutions are discussed and some physical and kinematical quantities are generalized and discussed. Our results are consistent with Yilmaz, Adcox et al and Back et al in four and five dimensions.