Article
Physics, Nuclear
M. Koussour, S. H. Shekh, M. Bennai
Summary: In this work, we investigated a spatially homogeneous and anisotropic Bianchi type-I space-time with the presence of Barrow holographic dark energy and matter. By considering the deceleration parameter, we studied the physical behavior of important cosmological parameters and constrained the model parameters using Hubble's parameter measurements.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2022)
Article
Multidisciplinary Sciences
Shivangi Rathore, S. Surendra Singh
Summary: This paper investigates an interacting dark energy model in LRS Bianchi type I cosmological model with a scalar field in the form of an exponential potential. By calculating the critical points and eigenvalues of the Jacobian matrix, we find that the Universe is accelerating and obtain the critical points and behavior of dark energy for different coupling parameters.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Mathematical
Y. S. Solanke, A. P. Kale, D. D. Pawar, V. J. Dagwal
Summary: We investigate LRS Bianchi type-I cosmological model in f(Q,T) theory of gravity with observational constraints. Two different functional forms of f(Q,T) = AQ + BT and f(Q,T) = AQ(n) + BT are considered, where A, B and n are model parameters. The best-fit values of constant parameters are obtained using least square method for observational constraints, and the available datasets such as Hubble dataset H(z), JLA, Pantheon, etc., are used by applying Root Mean Squared Error (RMSE) formula.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Sabiha Qazi, Kottakkaran Sooppy Nisar, Fiaz Hussain, Arshad Ali, Taseer Muhammad, Muhammad Ramzan, Sirajul Haq
Summary: The aim of this paper is to discuss exact Bianchi-type V cosmological solutions in f(T) gravity using conformal vector fields (CVFs) that satisfy energy conditions. The Einstein field equations (EFEs) are derived for Bianchi type V spacetimes in f(T) gravity. The exact Bianchi type V metrics in f(T) gravity are formulated by imposing constraints on space-time components. The dynamical parameters of the obtained solutions are plotted against cosmic time to observe their behavior, and the metrics are analyzed using CVFs to determine conservation laws and cosmological constraints.
RESULTS IN PHYSICS
(2023)
Article
Astronomy & Astrophysics
M. Koussour, S. H. Shekh, M. Govender, M. Bennai
Summary: In this paper, the Bianchi type-I cosmological model is discussed in the framework of symmetric teleparallel gravity, specifically f(Q) gravity where the non-metricity term Q accounts for the gravitational interaction. A particular form of the f(Q) function, f(Q) = lambda Qn, is considered, with lambda and n being the dynamical model parameters. This choice leads to a hybrid scale factor that describes the relationship between cosmic time and redshift, representing a Lambda CDM model of the Universe with a transition from deceleration to acceleration. The best values for the model parameters, alpha and beta, are estimated based on current observational datasets.
JOURNAL OF HIGH ENERGY ASTROPHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Shabeela Malik, Fiaz Hussain, Taotao Sui, Arshad Ali, Sirajul Haq, Muhammad Ramzan
Summary: The research focuses on investigating conformal vector fields (CVFs) of Bianchi type I space-times in modified teleparallel gravity (MTG). By classifying the space-times, the study identified 31 distinct Bianchi type I classes in MTG, and found that only one class formulates conformally non-flat space-times that admit proper CVFs. In other cases, the space-times either become conformally flat or tend to admit homothetic vector fields or Killing vector fields. The dimension of CVFs for Bianchi type I space-times in MTG was found to be three, four, five, six, and fifteen, and the physical parameters associated with each solution were calculated. Moreover, the solutions were classified via energy conditions to discuss physically viable results.
RESULTS IN PHYSICS
(2023)
Article
Physics, Mathematical
M. Koussour, M. Bennai
Summary: This paper presents a spatially homogeneous and anisotropic cosmological model with a viscous bulk fluid in f(R,T) gravity. The field equations are solved explicitly, and the behavior of the deceleration parameter is discussed, revealing two phases in the universe. The paper also calculates various physical and geometric properties and discusses the energy conditions and the Om(z) analysis.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Koussour, M. Bennai
Summary: In this work, we studied a cosmological model of Bianchi type-I Universe in teleparallel gravity. We assumed a linear relationship between the deceleration parameter and the Hubble parameter to obtain the cosmological solution. The model shows a transition from deceleration to acceleration in the history of our Universe. We discussed various physical and geometric properties such as the Hubble parameter, deceleration parameter, energy density, pressure, and equation of state parameter, and compared them with observational data. We also analyzed the behavior of other parameters and tested the validity of the model through stability analysis and energy conditions.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Physics, Mathematical
A. A. Coley, R. J. Van den Hoogen
Summary: Using a recently developed algorithm, we determine the completely general Bianchi type I teleparallel geometry, with preferred coordinates and a preferred co-frame. The remaining gauge freedom is allocated to the choice of spin connection. By solving the symmetry constraints on the spin connection, a general class of Bianchi type I teleparallel geometries is derived. This general class naturally breaks into two sub-classes, and we provide examples in F(T) teleparallel gravity to illustrate the differences.
JOURNAL OF MATHEMATICAL PHYSICS
(2023)
Article
Astronomy & Astrophysics
Anil Kumar Yadav, Avinash K. Yadav, Manvinder Singh, Rajendra Prasad, Nafis Ahmad, Kangujam Priyokumar Singh
Summary: This study investigates a bulk viscous universe with dominance of dark energy in Bianchi type I space-time and constrains its parameters using observational data, showing tensions with the corresponding Planck collaboration values. The derived model exhibits transitioning properties and has constraints that marginally depart from the ΛCDM model of the universe.
Article
Astronomy & Astrophysics
A. Mussatayeva, N. Myrzakulov, M. Koussour
Summary: In this paper, the authors investigate the parametrization of the effective equation of state (EoS) parameter within the framework of f(Q) symmetric teleparallel gravity. They derive the cosmological solution of the Hubble parameter H(z) using a specific parametrization and a power-law model of f(Q) theory. The model parameters are constrained using observational data, and the stability of the model is confirmed through a stability analysis.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Multidisciplinary Sciences
Ahmed M. Al-Haysah, A. H. Hasmani
Summary: In this paper, the Bianchi type-I string cosmological model is studied by combining Kaluza-Klein (KK) theory and f (R) theory of gravity. Various forms of the function f(R) are assumed to obtain physically significant and viable solutions, and some physical and geometrical properties of the model are discussed.
Article
Astronomy & Astrophysics
Piyali Bhar, Juan M. Z. Pretel
Summary: In this study, the relativistic structure of compact stars within the framework of f (Q) gravity is investigated. The results show that the physical characteristics of dark energy stars and quark stars can be explained using metric potentials and equations of state for dense matter, which is important for understanding stellar structure.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Raja Solanki, Avik De, P. K. Sahoo
Summary: In this study, the fundamental nature and evolution mechanism of dark energy in theoretical physics are explored using modified symmetric teleparallel gravity. The behavior of dark energy with different model parameters is analyzed, and it is found that it can exhibit quintessence or phantom scenario-like behavior. The study suggests that the geometrical generalization of general relativity can be a viable candidate for explaining the origin of dark energy.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
S. H. Shekh
Summary: This study dedicates to the dynamical investigation of models of holographic dark energy using FLRW cosmological model in the context of modified gravity, where the Lagrangian is the arbitrary function of the trace of the non-metricity tensor Q in f(Q) gravity. It discusses the features of the derived cosmological model in terms of the relation between cosmic time and redshift, as well as the evolution trajectories of the equation of state parameter and stability parameters in the evolving universe. The classification of the field equations towards f(Q) = Q + mQ(n) reveals that the model is purely accelerating corresponds to 0 <= q <= -1.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Astronomy & Astrophysics
S. H. Shekh, A. Bouali, G. Mustafa, A. Pradhan, F. Javed
Summary: In this study, the f(Q) gravity theory is used to analyze the rapid expansion of the Universe. The non-metricity scalar Q is the key parameter characterizing the gravitational interaction. By considering various observational data, we evaluate the model parameters and find that the Universe is currently in the acceleration phase. Additionally, we study different f(Q) gravity models and investigate their implications for cosmological parameters.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Multidisciplinary Sciences
Salim Harun Shekh, Nurgissa Myrzakulov, Anirudh Pradhan, Assem Mussatayeva
Summary: In this study, the authors work on the parametrization approach towards Hubble's parameter in the frame of modified teleparallel Gauss-Bonnet gravity. They investigate the cosmological history from early-time inflation to late-time acceleration expansion using the torsion invariant T and the teleparallel equivalent of the Gauss-Bonnet term T-G. A transition scenario from a decelerating phase to an accelerating phase of cosmic evolution has been detected.
Article
Physics, Mathematical
A. Hanin, M. Koussour, Z. Sakhi, M. Bennai
Summary: In this paper, we consider the modified symmetric teleparallel theory of gravity or f(Q) gravity, where Q represents the nonmetricity scalar. We discuss the behavior of various cosmographic and cosmological parameters under the assumption of a power-law form for the function f(Q) and the deceleration parameter form as a divergence-free parametrization. The results suggest that our cosmological f(Q) models behave like quintessence dark energy.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2023)
Article
Physics, Multidisciplinary
M. Koussour, S. Dahmani, M. Bennai, T. Ouali
Summary: In this paper, the authors examined a modified symmetric teleparallel gravity theory where the gravitational Lagrangian is defined by an arbitrary function of a non-metricity scalar Q. They used data from OHD and Pantheon+ datasets to constrain the model parameters and found that the obtained results were consistent with observation values. They studied the physical behavior of cosmological parameters and confirmed that the models described the current acceleration of the Universe's expansion. The EoS parameter indicated that the cosmological fluid behaved like a quintessence dark energy model.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Astronomy & Astrophysics
M. Koussour, S. H. Shekh, M. Govender, M. Bennai
Summary: In this paper, the Bianchi type-I cosmological model is discussed in the framework of symmetric teleparallel gravity, specifically f(Q) gravity where the non-metricity term Q accounts for the gravitational interaction. A particular form of the f(Q) function, f(Q) = lambda Qn, is considered, with lambda and n being the dynamical model parameters. This choice leads to a hybrid scale factor that describes the relationship between cosmic time and redshift, representing a Lambda CDM model of the Universe with a transition from deceleration to acceleration. The best values for the model parameters, alpha and beta, are estimated based on current observational datasets.
JOURNAL OF HIGH ENERGY ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
S. H. Shekh, A. Bouali, Anirudh Pradhan, A. Beesham
Summary: In this study, we investigate the late-time acceleration of the universe in f(Q, T) gravity, proposing a new scale factor to explore the solutions. By analyzing various data sets, we find that the universe undergoes a transition from deceleration to acceleration. Finally, we present an appraisal of our analysis.
JOURNAL OF HIGH ENERGY ASTROPHYSICS
(2023)
Article
Physics, Multidisciplinary
N. Myrzakulov, M. Koussour, Alnadhief H. A. Alfedeel, Amare Abebe
Summary: In this study, a Bayesian analysis was conducted on recent observational datasets to investigate the evolution of the EoS parameter in dark energy models. The results indicate that the present Universe is in a quintessence phase and undergoing accelerated expansion.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Multidisciplinary Sciences
A. P. Kale, Y. S. Solanke, S. H. Shekh, A. Pradhan
Summary: This study examines the f(Q, T) theory of gravity, discusses two different forms of the theory, analyzes the physical properties of the models, and obtains the best-fit values using the least squares method.
Article
Physics, Multidisciplinary
N. Myrzakulov, M. Koussour, Alnadhief H. A. Alfedeel, E. Hassan
Summary: We reconstruct the effective equation of state (EoS) in a homogeneous and isotropic universe composed of matter and dark energy using a dataset of cosmic chronometer data points, baryon acoustic oscillation data points, and type Ia supernova data points. The calculated cosmological parameters show behavior consistent with an accelerated universe scenario.
PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS
(2023)
Article
Physics, Particles & Fields
Dhruba Jyoti Gogoi, Ali Ovgun, M. Koussour
Summary: In this work, we studied the quasinormal modes of a black hole in f(Q) Sigma nin f(Q) gravity using the Bernstein spectral method, and validated the method with the Pade averaged higher-order WKB approximation method. We considered scalar and electromagnetic perturbations in the black hole spacetime and obtained the corresponding quasinormal modes. We found that the quasinormal frequencies in scalar perturbation are higher than those in electromagnetic perturbation for a non-vanishing nonmetricity scalar Q0. However, the damping rate of gravitational waves is higher for electromagnetic perturbation. Time domain profiles for both types of perturbations were also investigated to confirm the quasinormal mode behavior.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Dan Wang, M. Koussour, Adnan Malik, N. Myrzakulov, G. Mustafa
Summary: In this study, a logarithmic parametrization form of energy density for scalar field dark energy is proposed within the framework of the standard theory of gravity, which allows for a necessary transition from decelerated to accelerated behavior of the Universe. The model is constrained by observational data, including cosmic chronometers datasets, baryonic acoustic oscillation datasets, and supernovae datasets, with two parameters alpha and ss. The combined analysis of these datasets confirms a transition redshift of z(tr) = 0.79(-0.02)(+0.02), consistent with recent observations. The study also provides constraints on the matter parameter density value and the present value of the Hubble parameter.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
N. Myrzakulov, M. Koussour, Dhruba Jyoti Gogoi
Summary: In this paper, a new parametrization of dark energy based on the Om(z) diagnostic tool behavior is proposed. A functional form of the Om(z) is investigated to predict phantom and quintessence, the popular dark energy dynamical models. The famous cosmological constant is also found for specific values of the model's parameters. The Markov Chain Monte Carlo approach is employed to constrain the cosmological model using Hubble, Pantheon samples, and BAO datasets. Finally, observational constraints are used to investigate the characteristics of dark energy evolution and compare the findings to cosmological predictions.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
M. Koussour, Avik De
Summary: This study examines the cosmological possibilities emerging from two specific classes of f(Q) models, finding that their specific parameter values are the best fits at the current level of accuracy. The evolution of energy density, pressure, and deceleration parameter for these models are further studied to conclude the accelerating behavior of the Universe.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
M. Koussour, M. Bennai
Summary: We investigate a spatially homogeneous and anisotropic Bianchi type-I space-time, considering two fluids (matter and holographic dark energy) as the content of the Universe, within the framework of general relativity. By choosing a hyperbolic function as the scale factor and fixing the parameters gamma > 0 and n > 1, we obtain exact solutions to Einstein's field equations. Our cosmological model exhibits an early deceleration phase followed by the current observed acceleration phase. The anisotropic parameter and other physical parameters are also discussed, and the results are consistent with recent astronomical observations.
JOURNAL OF ASTROPHYSICS AND ASTRONOMY
(2023)
