# Ertan GüdekliIstanbul University · Department of Physics

Ertan Güdekli

Dr.

## About

38

Publications

3,630

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129

Citations

Introduction

Ertan Güdekli currently works at the Department of Physics, Istanbul University. Ertan does research in Theoretical Physics , cosmology and Dynamics systems.

Research Experience

September 1996 - present

**Istanbul University**

Position

- Professor (Assistant)

## Publications

Publications (38)

Extended $f(R)$ theories of gravity have been investigated from the symmetry
point of view. We briefly has been investigated Noether symmetry of two types
of extended $f(R)$ theories: $f(R,T)$ theory, in which curvature is coupled non
minimally to the trace of energy momentum tensor $T_{\mu\nu}$ and mimetic $f
(R) $ gravity, a theory with a scalar...

We investigate Friedmann–Lamaitre–Robertson–Walker (FLRW) models with modified Chaplygin gas and cosmological constant, using dynamical system methods. We assume $$p=(\gamma -1)\mu -\dfrac{A}{\mu ^\alpha }$$ p = ( γ - 1 ) μ - A μ α as equation of state where $$\mu$$ μ is the matter-energy density, p is the pressure, $$\alpha$$ α is a parameter whic...

Motivated by the work of Saridakis (Phys. Rev. D102, 123525 (2020)), the present study reports the cosmological consequences of Barrow holographic dark energy (HDE) and its thermodynamics. The literature demonstrates that dark energy (DE) may result from electroweak symmetry breaking that triggers a phase transition from early inflation to late-tim...

Citation: Sarkar, A.; Chattopadhyay, S.; Güdekli, E. A Regression Based Approach to the Observational Hubble Parameter Data through Holographic Chaplygin Gas. Symmetry 2021, 13, 701. https://

This paper deals with the Locally rotationally symmetric (LRS) Bianchi type-I universe model in Mimetic Gravity Theory assuming it an extended form of General Relativity Theory. It was proclaimed as a conformal transformation of the Einstein-Hilbert action from Einstein frame to Jordon frame. At the outset, we have proposed a potential function on...

Received Abstract Sixteen machine learning methods including K-Nearest-Neighbor, Random Forest, Additive Regression, Lineer Regression and M5P etc. were used to estimate the cosmic radiation dose for different international flights related with Istanbul and Ankara Airports in Turkey. Latitude, longlitude and depth were used as inputs to the develop...

As discussed in the previous section, business process modeling does not add value without further validation and analysis of the business process model. Similarly, process analysis is of little value if it does not help to improve or optimize the business process. Process improvement can occur using appropriate formal methods that support both mod...

The work reported in this paper demonstrates the cosmology of f (Q) gravity and the reconstruction of various associated parameters with different versions of holographic dark energy with generalized cutoffs , where Q = 6H 2. The Universe is considered to be filled with viscous fluid characterized by a viscous pressure Π = −3Hξ, where ξ = ξ 0 + ξ 1...

As it is known that General Theory of Relativity does not explain the current acceleration of the universe, so there are many attempts to generalize this theory in order to explain the cosmic acceleration without introducing some dark components such as the Dark Energy. Because of the crowd of models in literature, a need to check the models accord...

In this paper, we focused on the study of anisotropic strange stars with anisotropic matter distribution in the framework of f(T,T)=αT(r)2+βT(r) model, where α, β are arbitrary constants, T and T represent the torsion scalar and trace of energy–momentum tensor, respectively. This model has interesting cosmological properties, in addition to providi...

In this paper, we study the -gravitation theory under the assumption that the standard matter-energy content of the universe is a perfect fluid with linear barotropic equation of state within the framework of Bianchi-Type III model from the class of homogeneous and anisotropic universe models. However, whether such a restriction lead to any contrad...

A recent work proposed that the recent cosmic passage to a cosmic acceleration era is the result of the existence of small anti-gravity sources in each galaxy and clusters of galaxies. In particular, a Swiss-cheese cosmology model, which relativistically integrates the contribution of all these anti-gravity sources on a galactic scale has been cons...

In a recent work, it has been proposed that the recent cosmic passage to a cosmic acceleration era is the result of the existence of small anti-gravity sources in each galaxy and clusters of galaxies. In particular, a swiss-cheese cosmology model which relativistically integrates the contribution of all these anti-gravity sources on galactic scale...

In this work, we have studied various cosmological parameters in the presence of viscous new Tsallis holographic dark energies for interacting scenarios in the framework of Chern–Simons modified gravity. The bulk viscosity has been considered with the bulk viscous pressure chosen in the form [Formula: see text]. Hubble parameter [Formula: see text]...

In our study we are interested in dissipative gravitational collapse of anisotropic spherically symmetric radiating star satisfying initially static Karmarkar condition in formalism of f(R, T ) gravity. Moreover, we have chosen a linear model f(R, T ) = f(R) + f(T ), where R is a Ricci scalar, T is a trace of energy-momentum tensor and λ is dimensi...

This paper investigates the new interior solution of stellar compact spheres in the framework of metric [Formula: see text] gravity. In this connection, we derived the Einstein field equations for static anisotropic spherically symmetric spacetime in the mechanism of Karmakar condition. The obtained results of the field equations have been studied...

In the present manuscript, we have constructed an anisotropic solution for spherically symmetric space-time that satisfies Karmarkar’s condition in the context of f(R,T) theory of gravity where R and T represent the Ricci scalar and the trace of Energy-momentum tensor, respectively. In order to achieve our goal, we chose a one of the gravitational...

Motivated by the work of Saridakis (Phys. Rev. D 102, 123525 (2020)), the present study reports the cosmological consequences of Barrow holographic dark energy (HDE) and its thermodynamics. Literatures demonstrate that Dark Energy (DE) may result from electroweak symmetry breaking that triggers a phase transition from early inflation to late time a...

This paper examines the cosmic evolution and current expansion for flat FRW universe through generalized ghost pilgrim dark energy model in [Formula: see text] gravity. For this purpose, we reconstruct the models in terms of red-shift parameter with respect to three scale factors, i.e. power-law, intermediate and a scale factor defining two unified...

The purpose of this work is to present stellar models for anisotropic matter distribution in the framework of [Formula: see text] gravity with torsion scalar [Formula: see text]. In this regard, we use the interior geometry of Tolman–Kuchowicz spacetime having the potential components of the form [Formula: see text] and [Formula: see text], where [...

In this study, cosmic radiation doses were calculated for domestic and international flights departing from Istanbul and furthermore for domestic flights departing from Ankara using a software program called CARI-7A and also a mathematical method approach. Main parameters for calculating cosmic radiation are vertical cut-off rigidity, flight durati...

It is well-known that F (R) and F (T) modified gravity theories are dynamically equivalent to some scalar-tensor gravity theories. In analogy to these F (R) and F (T) modified gravity theories, it is interesting to study the conformal symmetry of the Myrzakulov gravity (MG). Note that in the MG, the curvature scalar R appearing in the gravitational...

In this study, the LRS (Local Rotational Symmetric) perfectly fluid Bianchi type - I- cosmological model is considered with the f(R,T) gravity. The particular case of f(R). f(T). The physical and kinematical properties of the model are studied. The exact solution of the field equations are obtained using the scalar expansion proportional to the she...

The coupled integrable dispersionless equations have a significant interest because of structure, integrability, and the possibility of obtaining a soliton solution. In this paper, we construct soliton surfaces for integrable dispersionless equation with self-consistent sources in Riemann space. The surfaces, arising from M-XXXII equation and their...

In this study, the LRS (Local Rotational Symmetric) perfectly fluid Bianchi type -I-cosmological model is considered with the F(R, T) gravity. The particular case of f1(R) = λ1R and f2(T) = λ2T are considered where λ1 and λ2 are real constant. [3].

In this article we study the Myrzakulov gravity with a fermion field described by a nonminimal action. The cases with a linear and nonlinear interaction of the gravitational and fermion fields are considered. It is shown that in the case of nonlinear interaction, Myrzakulov gravity can describe the accelerated expansion of the universe.

In this paper, we consider the Myrzakulov gravity (MG), that is the F (R, T) gravity, where R is the curvature scalar and T is the torsion scalar. The MG with f-essence is studied. The particular case of MG, when F (R, T) = αR + βT is considered, where α and β are some constants.

In this paper, we consider the Myrzakulov gravity with the action S37 = d 4 x √ −g[F (R, T)+Lm], where R is the curvature scalar and T is the torsion scalar. The particular case, when F (R, T) = αR + βT is studied in detail. As the matter Lagrangian Lm, we take the Myrzakulov fermionic model or accordingly to the notations of [7], the M33-model (f-...

In this paper, we investigate the dynamics of the universe on the background of f-essence when a non-minimal coupling with gravity. Field equations are obtained and using the Noether theorem, explicit forms of the coupling function and the Lagrange function of the f-essence were obtained. Accordingly, for this model, the cosmological parameters tha...

In this paper, we investigate \(f(T)\) cosmology and find an exact solution for \(f\) which gives a Little Rip cosmology. Also, considering accelerating cosmology with dark matter, the time-dependent solution is found. For these cases, by using solutions obtained from \(f(T)\) gravity we find expressions for \(\omega\) and \(\varLambda\) defined as...

In this paper, we have investigated trace-anomaly (TA) driven inflation in Generalized Teleparallel gravity (namely f(T)). A quasi de Sitter (dS) scenario for inflation is proposed like in the case of R
2 gravity. It has been found that in f(T) gravity, the dS solution for inflation is unstable due to the conformal anomaly (CA). As an illustrative...

We have been studied the model of light Galileon with translational shift
symmetry $\phi\to \phi+c$. The matter Lagrangian is presented in the form
$\mathcal{L}_{\phi}= -\eta (\partial \phi)^2+\beta
G^{\mu\nu}\partial_{\mu}\phi\partial_{\nu}\phi$. We have been addressed two
issues: the first is that, we have been proven that, this type of Galileons...

We discuss a comprehensive description of the geometry of the brane-world cosmologies, and present bulk and brane structure and matching between brane and bulk metrics. It is clear that the possibility of the matching condition is not always obvious and therefore it requires a separate analysis. In this study we have shown, under the assumption of...

## Projects

Project (1)

In this project , using the orthonormal tetrad formalism, we give a systematic and detailed derivation of the full set of cosmic evolution and constraint equations in Myrzakulov Gravity models containing an orthogonal, one component fluid.