Article
Physics, Multidisciplinary
Rabia Saleem, M. Israr Aslam, M. Zubair
Summary: In this study, the exact interior anisotropic solutions of compact stars are found under the f(T, T) gravity framework, considering Krori-Barua space-time. By evaluating the unknown model parameters through matching the exterior and interior space-time, it is observed that the results satisfy all necessary and sufficient physical conditions, making them physically viable.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Physics, Mathematical
Puja Mukherjee, Ujjal Debnath, Anirudh Pradhan
Summary: In this article, we discussed the accretion phenomenon of two intriguing forms of dark energies, MCJG and MCAG, onto a four-dimensional Schwarzschild black hole. By deducing the rate of change of mass and evolving the required mass in terms of the redshift z, we plotted mass versus redshift graphs for different values of k and a in MCJG and MCAG, respectively. Additionally, we portrayed mass versus redshift graphs in different stages of the FRW universe. It was found that both MCJG and MCAG accretion resulted in an increasing pattern of black hole mass. However, in the case of a phantom energy-filled universe, the black hole mass exhibited a decreasing nature. Moreover, during the ?CDM stage of the universe, MCAG accretion primarily led to an increase in mass followed by a gradual decrease.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2023)
Article
Astronomy & Astrophysics
Saibal Ray, Sunil Kumar Tripathy, Rikpratik Sengupta, Bibhudutta Bal, Sonali Monalisa Rout
Summary: In this study, we compare the Kantowski-Sachs and Bianchi-I anisotropic universes and use Modified Chaplygin gas as the matter source. We obtain the volume and scale factors of the anisotropic universes and investigate the washing out of initial anisotropy. The results provide insights into the role of MCG in these models.
Article
Physics, Multidisciplinary
Rabia Saleem, Abdul Wahab, Iqra Shahid
Summary: This paper contributes to the study of the effectiveness of Rastall gravity (RG) by exploring the mechanism of warm viscous inflation inspired by modified Chaplygin gas (MCG). The authors establish a current model using an intermediate form of the scale factor and calculate the analytic solution for inflaton and the effective potential necessary to cause inflation, as well as the entropy density under slow-roll conditions. They further investigate a high dissipative regime, considering both constant and variable dissipative and viscous coefficients. The exact solutions obtained are used to examine the compatibility of RG with the Planck 2018 data. The paper concludes that RG, along with the modification of the CG model, can lead to significant changes in the early universe.
Article
Physics, Multidisciplinary
F. Mavoa, H. Hova, G. Ganiou, S. Houndjo, F. Ahloui, E. Baffou, A. D. Kanfon
Summary: This paper investigates the interaction effect between dark energy and two types of viscous Chaplygin gas models within the modified gravity and Friedmann-Robertson-Walker Universe framework. The study considers two main interactions, namely between the generalized Chaplygin gas and dark energy, and between the modified Chaplygin gas and dark energy. The resulting modified Friedmann equations, energy density, and pressure are obtained for both cases, showing how shear and bulk viscosities affect the cosmological evolution of the Universe.
INDIAN JOURNAL OF PHYSICS
(2023)
Article
Astronomy & Astrophysics
Ujjal Debnath, Behnam Pourhassan, Izzet Sakalli
Summary: In this paper, a new charged AdS black hole with modified cosmic Chaplygin gas (MCCG) is constructed and its thermodynamics, energy conditions, and the efficiency of a heat engine are studied. The results show that the black hole is stable under certain conditions and can work as a heat engine.
MODERN PHYSICS LETTERS A
(2022)
Article
Astronomy & Astrophysics
Ujjal Debnath
Summary: In this study, we investigated the modified Chaplygin gas in the background of Brans-Dicke theory, considering the presence of radiation and dark matter, and constrained the model with various observational data for comparison. The best fit parameters for the ΛCDM model and MCG model in BD theory were obtained through joint data analysis, along with contour plots at different confidence levels. Analysis of Delta AIC and Delta BIC was also conducted for these models in both Einstein's gravity and BD theory.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Physics, Nuclear
Ujjal Debnath
Summary: This paper explores the flat FRW model of the universe with modified Chaplygin gas as the fluid source, deriving modified equations of state and studying the evolution of cosmological parameters through observational data analysis. The classical stability of the models is examined by determining the values of square speed of sound for the expansion of the universe with best-fit model parameters.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2021)
Article
Physics, Multidisciplinary
Gaurav N. Gadbail, Simran Arora, P. K. Sahoo
Summary: In this study, we use the viscous generalized Chaplygin gas (VGCG) model, which is a hybrid model of bulk viscosity and generalized Chaplygin gas, as an alternate dark fluid of the universe. We investigate the dynamics of the VGCG model in the non-metricity gravity framework using a functional form f(Q) = /3Qn, with /3 and n being arbitrary constants. To constrain model parameters, we utilize observational datasets such as Observational Hubble data, Baryon Acoustic Oscillations, and Type Ia supernovae data. Our results show a transition from deceleration to an acceleration phase in the evolution of the deceleration parameter q and the equation of state (EoS) parameter w, with deviations from the ΛCDM model.
Article
Physics, Multidisciplinary
Xiang-Qian Li, Bo Chen, Li-Li Xing
Summary: The Lovelock theory of gravity is extended to higher dimensions, and the thermodynamical stability of a static spherically-symmetric black hole surrounded by modified Chaplygin gas is considered. The study reveals the existence of different phases of thermodynamical stability, which are influenced by the parameters of the model.
Article
Astronomy & Astrophysics
Fidele Twagirayezu, Abraham Ayirwanda, Albert Munyeshyaka, Solange Mukeshimana, Joseph Ntahompagaze, Leon Fidele Ruganzu Uwimbabazi
Summary: This work investigates cosmological perturbation in a mixture of standard matter, Chaplygin gas, and Gauss-Bonnet fluids within the framework of modified f(G) gravity using a 1+3 covariant approach. Linear perturbation equations are derived by defining gradient variables. Scalar and redshift transformations are applied to consider both original and generalized Chaplygin gas models under Gauss-Bonnet gravity. A polynomial f(G) gravity model is used for pedagogical purposes to solve the perturbation equations for short- and long-wavelength modes and study the late-time evolution. Numerical solutions are obtained, showing that energy overdensity perturbations decay with increasing redshift. The treatment recovers the results of general relativity in limiting cases.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2023)
Article
Engineering, Environmental
Yisa Zhou, Ya Zhang, Jian Xue, Rui Wang, Zongjie Yin, Li Ding, Haihui Wang
Summary: In this study, a continuous g-C3N4-GO membrane with excellent H2 permeation performance and good stability was successfully prepared by utilizing graphene oxide nanosheets to cover and repair defects in two-dimensional graphitic carbon nitride (g-C3N4) nanosheets.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Mechanics
Deepika Sharma, Randheer Singh
Summary: This manuscript derives a system of partial differential equations (PDEs) for a one-dimensional isentropic two-phase flow model with a non-constant source term and non-ideal modified Chaplygin gas. The model is simplified to an equivalent system of ordinary differential equations (ODEs) using the Lie group scheme. The transport equation for the singular surface is obtained through compatibility conditions and solved numerically in conjunction with the system of ODEs. The effects of flow inclination and non-idealness on the amplitude of steepened wave (or singular surface) are investigated.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2023)
Article
Astronomy & Astrophysics
Ujjal Debnath
Summary: In this paper, the authors investigate the thermodynamic properties and energy conditions of n-dimensional asymptotically Anti-de Sitter black holes using the polytropic gas and modified Chaplygin gas as the thermodynamic systems. They found solutions for the Einstein field equations and examined the energy conditions for the fluid sources in the black hole system. Furthermore, the authors studied the heat engine phenomena and analyzed the work done with the efficiencies due to different cycles.
MODERN PHYSICS LETTERS A
(2022)
Article
Physics, Mathematical
Weifeng Jiang, Tong Li, Zhen Wang, Shutian Fang
Summary: In this article, the Riemann solutions of the compressible Euler equations in non-isentropic modified Chaplygin gas are constructed, and the formation of delta-shock waves is discovered through extending the solvable region of the pure Chaplygin gas state. By studying the limiting behavior, it is found that the limit of the Riemann solutions of modified Chaplygin gas is the same as pure Chaplygin gas including the delta-shock waves. Finally, numerical simulations are performed to validate the theoretical analysis.
JOURNAL OF MATHEMATICAL PHYSICS
(2021)
Article
Physics, Mathematical
Kimet Jusufi, Mustapha Azreg-Ainou, Mubasher Jamil, Tao Zhu
Summary: This paper investigates the effects of the Generalized Uncertainty Principle (GUP) on the shadow and quasinormal modes (QNMs) of GUP-modified Kerr black holes. The study reveals that the GUP modification increases the curvature radius of the shadow and that it increases linearly with the GUP parameter. By using observational data and fitting techniques, the upper limits of the GUP parameter and the correction parameter in the modified black hole metric are determined.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Astronomy & Astrophysics
Kimet Jusufi, Mustapha Azreg-Ainou, Mubasher Jamil, Emmanuel N. Saridakis
Summary: Using observations of the central black hole and stars, we extract constraints on Barrow entropy, finding an upper bound less strong than the Big Bang Nucleosynthesis but significantly stronger than late-time cosmological constraints.
Article
Astronomy & Astrophysics
Javlon Rayimbaev, Bushra Majeed, Mubasher Jamil, Kimet Jusufi, Anzhong Wang
Summary: In this article, we investigate the particle dynamics around a Bardeen-Kiselev black hole, including its geometrical properties, the dynamics of test particles, and the relationship with rotating Kerr black hole.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
Kimet Jusufi, Mustapha Azreg-Ainou, Mubasher Jamil, Qiang Wu
Summary: This paper focuses on the relationship between quasinormal modes (QNMs) and a rotating black hole shadow, using the example of a quantum deformed Kerr black hole. The study shows that, in the eikonal limit, the real part of QNMs is related to the Keplerian frequency for equatorial orbits. The paper also explores the typical shadow radius, computes the corresponding modes, and investigates the thermodynamical stability of the quantum deformed Kerr black hole, as well as other astrophysical applications.
Article
Mathematics, Applied
Y. Myrzakulov, A. Sharlez, D. Kenzhalin, S. Myrzakul, G. Yergaliyeva
Summary: The article investigates cosmological solutions of the Starobinsky model in a flat inhomogeneous viscous Universe. It provides a brief overview of the F(R) theory of gravity and then focuses on the specific cosmological model of the Starobinsky F(R) = alpha R + beta R-2 model. The dynamics of the Hubble parameter H, viscosity, and time are analyzed, revealing a transition from accelerated expansion to instantaneous compression at a certain point in time, followed by a cessation of expansion.
INTERNATIONAL JOURNAL OF MATHEMATICS AND PHYSICS
(2022)
Article
Physics, Mathematical
Yerlan Myrzakulov, Kairat Myrzakulov, Sudhaker Upadhyay, Dharm Veer Singh
Summary: In this paper, an exact regular black hole solution in the Einstein-Gauss-Bonnet theory coupled with nonlinear matter fields is presented. It is a generalization of a regular Einstein-Gauss-Bonnet black hole in 5D AdS spacetime. The obtained solution has the same causal structure as the Boulware-Deser black hole solution, except for the curvature singularity at the center. The solution incorporates the Boulware-Deser black holes in the absence of deviation parameters and satisfies a modified first law of thermodynamics. The stability of the black hole solution is discussed, revealing a double phase transition and the existence of critical points.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2023)
Article
Astronomy & Astrophysics
Javlon Rayimbaev, Ahmadjon Abdujabbarov, Mubasher Jamil, Wen-Biao Han, Malika Khudoyberdieva
Summary: This paper discusses the motion of various types of charged, magnetized, and neutral test particles near static and spherically symmetric electrically charged black holes in the Einstein-/Ether gravitational theory. The effects of the free parameters in the theory on particle motion in curved spacetime are analyzed, focusing on the stability of circular and radially varying orbits for different types of particles. The behavior of charged particle motion around black holes with a uniform magnetic field is investigated, and values of the parameters c13 and c14 are proposed to model astrophysical black holes based on the spin of Kerr black holes.
MODERN PHYSICS LETTERS A
(2022)
Article
Physics, Multidisciplinary
Sudhaker Upadhyay, Surajit Mandal, Yerlan Myrzakulov, Kairat Myrzakulov
Summary: In this paper, we discuss the behavior of light in a charged black hole solution within the context of massive gravity. By analyzing the optical geometry of the black hole solution, we determine the Gaussian curvature in the weak gravitational lensing regime. Additionally, we investigate the deflection angle of light rays in both plasma and non-plasma media using the Gauss-Bonnet theorem. We also examine the implications of the Regge-Wheeler equation and derive strict bounds on the greybody factors of linearly charged massive BTZ black holes. Moreover, we study the shadow or silhouette produced by charged massive BTZ black holes, and explore the effects of charge and cosmological constant on the shadow radius.
Article
Physics, Nuclear
Farruh Atamurotov, Mubasher Jamil, Kimet Jusufi
Summary: In this study, the optical properties of a renormalization group improved Schwarzschild black hole in a plasma medium are investigated. The deflection angle of light in the weak gravity regime is computed for uniform and non-uniform plasma media, revealing the modifications caused by the plasma medium. The effects of plasma media play an important role in the optical appearance of black holes.
Article
Physics, Nuclear
Surajit Mandal, Sudhaker Upadhyay, Yerlan Myrzakulov, Gulmira Yergaliyeva
Summary: In this paper, the authors discuss the shadow cast by the charged Reissner-Nordstrom (RN) anti-de Sitter (AdS) black hole. They calculate the geodesic equations for null particles using the Killing equation and Hamilton-Jacobi equation, and determine the celestial coordinates and shadow radius of the RN AdS black hole. The authors present a graphical analysis of the black hole shadow, showing it to be a perfectly dark circle. They also investigate the effects of charge, cosmological constant, and plasma medium on the shadow radius and energy emission rate of the RN AdS black hole.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2023)
Article
Physics, Particles & Fields
Prosenjit Paul, Sudhaker Upadhyay, Yerlan Myrzakulov, Dharm Veer Singh, Kairat Myrzakulov
Summary: In this paper, the authors investigate the thermodynamics of nonlinearly charged AdS black holes in four-dimensional critical gravity under the effect of small statistical fluctuations. They calculate the correction to the thermodynamics of these black holes at the leading order and discuss their stability under fluctuation. The authors also derive the isothermal and adiabatic compressibilities and study the impact of small fluctuations on the equation of states and the P - v diagram of the black holes.
Article
Physics, Multidisciplinary
S. A. Myrzakulova, O. Razina, N. A. Myrzakulov, A. B. Altaybaeva
Summary: In this paper, a periodic cosmological model is studied and the corresponding parameters and graphs are calculated. Additionally, the consistency of this model with previously proposed ones is explored. This has important implications for studying dark energy and cosmic expansion.
RECENT CONTRIBUTIONS TO PHYSICS
(2022)
Article
Physics, Multidisciplinary
D. Z. Rakhatov, P. Y. Tsyba, O. Razina
Summary: In this article, the Gauss-Bonnet model of gravity is investigated in a flat, isotropic and homogeneous universe. The solutions for the scale factor with power and modified power dependence on time are found using the method of variation. It is shown that the model satisfies the energy conditions but not the SEC. The parameters of the model correspond to modern cosmological data, confirming its realism in an accelerated expanding universe.
RECENT CONTRIBUTIONS TO PHYSICS
(2022)
Article
Physics, Particles & Fields
Kimet Jusufi, Saurabh Kumar, Mustapha Azreg-Ainou, Mubasher Jamil, Qiang Wu, Cosimo Bambi
Summary: In this study, we investigate the possibility of a wormhole as a candidate for the central object of Sgr A(star) and test this idea by constraining their geometry using the motion of S2 star and the reconstructed shadow images. We consider three wormhole models and find that they satisfy the flare out condition. We also explore the accretion of infalling gas model and study the accretion rate, electromagnetic radiation intensity, and shadow images.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
Sanjar Shaymatov, Mubasher Jamil, Kimet Jusufi, Kazuharu Bamba
Summary: In this study, we investigate the dynamics of test particles around a magnetized Ernst black hole, taking into account its surrounding magnetic field. We find that the magnetic field has a significant impact on the radius of the innermost stable circular orbit (ISCO) and the epicyclic frequencies, especially for charged particles. By analyzing the astrophysical quasiperiodic oscillation (QPO) data of three microquasars, we determine the order of magnitude of the magnetic field.
EUROPEAN PHYSICAL JOURNAL C
(2022)
