Article
Physics, Particles & Fields
S. A. Mardan, I Noureen, A. Khalid
Summary: The study successfully constructed a relativistic core-envelope model, matching core, envelope, and the Reissner Nordstrom exterior regions, discussing various physical parameters in compact stars while maintaining non-singularity and continuity. The impact of a charged compact object together with the core-envelope model on mass, radius, and compactification factor was described through graphical representation in both core and envelope regions. The stability of the model was analyzed using Tolman-Oppenheimer-Volkoff equations and radial sound speed.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Nicolas Sanchis-Gual, Miguel Zilhao, Vitor Cardoso
Summary: This study explores the dynamics of boson stars in the presence of axionic couplings, revealing new instabilities and decay phenomena, as well as discussing collisions and interactions between boson stars and the potential electromagnetic and gravitational signals that may be generated.
Article
Chemistry, Physical
Muhammad Hassan, Connor Williamson, Joshua Baptiste, Stefanie Braun, Anthony J. Stace, Elena Besley, Benjamin Stamm
Summary: This study presents a quantitative method for evaluating the electrostatic interactions between dielectric particles in an external electric field, taking into account inhomogeneous charge distributions and pointlike charges on the particle surface. The numerical results validate the proposed method and highlight the limitations of the fixed dipole approximation at small particle separations. The method is also applied to investigate the stability and melting of ionic colloidal crystals under an external electric field.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Materials Science, Multidisciplinary
Guangtao Cao, He-Xiu Xu, Lei-Ming Zhou, Yan Deng, Yixuan Zeng, Shaohua Dong, Qing Zhang, Yangjun Li, Hui Yang, Qinghai Song, Xinke Liu, Ying Li, Cheng-Wei Qiu
Summary: Infrared metasurfaces are revolutionary tools for manipulating electromagnetic waves, with potential applications in military and civilian fields. These surfaces can steer electromagnetic waves within subwavelength scale with full degrees of freedom, allowing for the development of various planar meta-devices.
Article
Astronomy & Astrophysics
P. Mafa Takisa, S. D. Maharaj, M. L. Lekala
Summary: This work models compact stars using an equation of state of dark matter with admixed matter, exploring physical features and mass limits, and showing the influence of the nonlinear term on matter distribution. In particular, the maximum stellar mass of PSRJ0030+0451 is found for the admixed matter distribution.
ASTROPHYSICS AND SPACE SCIENCE
(2021)
Article
Astronomy & Astrophysics
Christian Ferko, Gautam Satishchandran, Savdeep Sethi
Summary: A general formalism has been developed for treating radiative degrees of freedom near I thorn in theories with an arbitrary Ricci-flat internal space. The radiative modes are encoded in a generalized news tensor which decomposes into components of gravitational, electromagnetic, and scalar. The preferred gauge simplifies the asymptotic analysis of the full nonlinear Einstein equations and extends the Bondi-Metzner-Sachs (BMS) group to include angle-dependent isometries of the internal space.
Article
Astronomy & Astrophysics
Kota Numajiri, Taishi Katsuragawa, Shin'ichi Nojiri
Summary: In this study, a compact star in general F(R) gravity is investigated. It is confirmed that an arbitrary relation between mass and radius of the compact star can be achieved by adjusting the functional form of F(R). It is also found that the functional form of F(R) is constrained by the solution of a differential equation for the polytropic equation of state.
Article
Physics, Particles & Fields
Yuan Yue, Peng-Bo Ding, Yong-Qiang Wang
Summary: In this paper, the model of bosonic matter with a nontrivial wormhole spacetime topology supported by a free phantom field is revisited. A new type of boson star with wormhole solutions, where the complex scalar field possesses full parity-odd symmetry, is obtained. The behavior of boson stars with wormhole approaches that of boson stars when the size of the throat is small, but is replaced by a loop structure when the size of the throat is intermediate. The complex scalar field can form two boson stars with opposite phase differences in the limit of vanishing throat size.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
M. V. S. Saketh, Justin Vines
Summary: In this paper, we study the scattering process of an incident gravitational plane wave off a massive spinning compact object within classical general relativity. We compute the amplitude of the asymptotic scattered wave, which provides valuable information about the object's response to external gravitational fields. By using an effective worldline theory, we describe the motion of the compact object and analyze the coupling between spin-induced higher multipole moments and space-time curvature. Our results show agreement with previous conjectures based on quantum scattering amplitudes.
Article
Physics, Multidisciplinary
Ramiro Cayuso, Pau Figueras, Tiago Franca, Luis Lehner
Summary: The majority of extensions to general relativity encounter mathematical pathologies, but here we present an approach to deal with and extract physical consequences from these extensions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Astronomy & Astrophysics
Shweta Saklany, Brajesh Pandey, Neeraj Pant
Summary: This study provides a simulation of the coupling of dark energy and baryonic matter using a super-dense pulsar as the model star. The analysis of various physical parameters indicates stable star formation. The proposed stellar model is free from singularities and meets the requisite stability criteria.
MODERN PHYSICS LETTERS A
(2022)
Article
Astronomy & Astrophysics
Andreas Bauswein, Gang Guo, Jr-Hua Lien, Yen-Hsun Lin, Meng-Ru Wu
Summary: In this study, the long-lasting gravitational wave emission from compact dark objects in binary neutron-star mergers is estimated. By performing relativistic simulations, it is found that these dark matter components can remain gravitationally bound and generate gravitational wave signals with frequencies in the kilohertz range. Furthermore, relations between the gravitational wave frequency of the dark matter components and the properties of the merger remnant are established. The detectability of these gravitational wave signals suggests that only dark matter objects with masses of about 0.01 to 0.1 times the solar mass can be observed with existing and projected gravitational wave instruments.
Article
Mathematics, Applied
Hyunjin Ahn, Seung-Yeal Ha, Myeongju Kang, Woojoo Shim
Summary: The study presents a relativistic counterpart of the Cucker-Smale model on Riemannian manifolds and examines its collective behavior. By replacing usual time derivatives with appropriate geometric quantities, the model is extended from Euclidean space to connected, complete, and smooth Riemannian manifolds. Concrete examples on the unit sphere and hyperbolic space show the emergence of weak velocity alignment in compact manifolds.
PHYSICA D-NONLINEAR PHENOMENA
(2021)
Article
Astronomy & Astrophysics
Yu-Peng Zhang, Yan-Bo Zeng, Yong-Qiang Wang, Shao-Wen Wei, Yu-Xiao Liu
Summary: This paper investigates the motion of a test particle in the spacetime of a rotating boson star and discusses the possible observable effects of astrophysical boson stars.
Article
Physics, Particles & Fields
J. W. Jape, S. D. Maharaj, J. M. Sunzu, J. M. Mkenyeleye
Summary: The translated passage discusses a new generalized regular charged anisotropic exact model with conformal symmetry in spherical spacetime. The model is examined for physical acceptability and found to meet various criteria, with some existing models also included as special cases. The use of conformal symmetry provides a generalized geometric framework for studying compact objects.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
S. K. Maurya, Francisco Tello-Ortiz, Saibal Ray
Summary: This new methodology effectively builds up self-gravitating structures by introducing additional matter fields and extra degrees of freedom to modify the energy-momentum tensor and mass function of the system.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Materials Science, Multidisciplinary
M. K. Jasim, S. K. Maurya, Saibal Ray, Dibyendu Shee, Debabrata Deb, Farook Rahaman
Summary: This paper discusses the existence of a compact strange (quark) star within the framework of Einstein's General Theory of Relativity with the Tolman V metric potential and uses the simplest form of MIT Bag equation of state to represent strange quark matter distribution. Various physical features and stability criteria are studied for different strange star candidates, and results show consistency with energy conditions, TOV equation, and adiabatic index. Different physical parameters are also calculated for three consecutive values of Bag constant, with a focus on the properties of strange star candidates with B = 90 MeV/fm³.
RESULTS IN PHYSICS
(2021)
Article
Physics, Multidisciplinary
Suparna Biswas, Debabrata Deb, Saibal Ray, B. K. Guha
Summary: This study presents spherically symmetric anisotropic charged strange stars under f(R, T) gravity framework, using a simplified MIT bag model equation of state to describe the Strange Quark Matter distribution inside the stars. By calculating the value of B-g from observed mass and radius values for the strange star candidate LMC X-4, the model shows that the coupling constant chi significantly affects the bag constant value. The model demonstrates consistency with physical conditions and offers a viable study on the nature of charged anisotropic massive stellar systems.
Article
Astronomy & Astrophysics
Sourav Roy Chowdhury, Debabrata Deb, Farook Rahaman, Saibal Ray, B. K. Guha
Summary: The behavior of the noncommutative radiating Schwarzschild black hole in Finslerian spacetime was studied, revealing variations in the number of horizons and minimal mass with the Finslerian parameter. The study also found changes in the maximum temperature and stability of the black hole with the Finslerian parameter. The presence of a stable black hole remnant was suggested, uniquely determined by Finslerian and noncommutative parameters.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Ines G. Salako, Chayan Ranjit, M. Khlopov, Saibal Ray, Utpal Mukhopadhyay
Summary: In this study, compact stellar models were examined within the framework of modified gravity theory, particularly of f(T, T) type. By assuming spherical symmetric static metric and utilizing conformal Killing vectors, solutions to the Einstein field equations in the spacetime of f(T, T) were obtained. These solutions, obtained by applying the MIT bag equation of state and considering strange quark matter, were tested through various physical tests to demonstrate the viability of the model.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2021)
Article
Astronomy & Astrophysics
Amna Ali, Sabiruddin Molla, Farook Rahaman, Ruhul Amin, Gurudas Mandal, Saibal Ray
Summary: This paper studies the static and spherically symmetric dilaton-axion black hole in the testing ground of the Solar system, constraining the parameters of the string motivated dilaton-axion form through classical tests of general relativity. The permissible range of these parameters is obtained from theoretical analysis based on the model and compared with observations.
Article
History & Philosophy Of Science
Saibal Ray, Utpal Mukhopadhyay, Rajinder Singh
Summary: Nikhilranjan Sen, also known as N.R. Sen, is recognized as the Father of Applied Mathematics and founder of the Calcutta School of Relativity Theory. He conducted his Ph.D. studies in Berlin under the guidance of Nobel Laureate Max von Laue, where he had the opportunity to interact with renowned physicists such as Max Planck and Albert Einstein.
EUROPEAN PHYSICAL JOURNAL H
(2021)
Article
Astronomy & Astrophysics
B. Mishra, A. S. Agrawal, S. K. Tripathy, Saibal Ray
Summary: In this study, the geometry of traversable wormholes in f(R) theory gravity, where R represents the Ricci scalar, was examined. Solutions for wormholes based on assumed f(R) functions were presented, with the assumption that the behavior of f(R) changes with a parameter a rather than the deceleration parameter. Three models were proposed based on physically motivated shape functions, and their behaviors were analyzed.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2021)
Article
Astronomy & Astrophysics
Biplab Paik, M. Yu Khlopov, Mehedi Kalam, Saibal Ray
Summary: This study investigates the impact of quantum effective gravity on cosmology, proposing a semi-classical method for constructing a regularized cosmological model and demonstrating the different characteristics of the new model cosmology at different energy phases.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Physics, Multidisciplinary
S. K. Tripathy, B. Mishra, Saibal Ray, Rikpratik Sengupta
Summary: Investigations into bouncing models within the framework of extended gravity theory reveal that model behavior is determined by parameters, the minimal matter-geometry coupling parameter in extended gravity can remove singularities, and violation of energy conditions can lead to evolution into phantom phase in some cases.
CHINESE JOURNAL OF PHYSICS
(2021)
Article
Physics, Multidisciplinary
S. K. Maurya, Ksh Newton Singh, Saibal Ray
Summary: This study applies the Brans-Dicke theory of gravitation as an alternative to general relativity for modeling anisotropic compact stellar objects. By considering specific conditions for the space-time, the field equations become solvable and the numerical solution for the Brans-Dicke scalar field phi fits well with a known function. The solutions set appears viable based on observational data.
CHINESE JOURNAL OF PHYSICS
(2021)
Article
Astronomy & Astrophysics
S. K. Tripathy, B. Mishra, Maxim Khlopov, Saibal Ray
Summary: This paper presents cosmological models with a hybrid scale factor (HSF) in the framework of general relativity (GR), which exhibit early deceleration and late-time acceleration. By discussing the dynamical aspects of these models with HSF in the presence of different matter fields, it mimics the present Universe.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2021)
Article
Astronomy & Astrophysics
Koushik Chakraborty, Farook Rahaman, Saibal Ray, Banashree Sen, Debabrata Deb
Summary: This article explores the geometry of wormholes in spiral galaxies under Lovelock gravity and finds a mathematical model to describe the existence of wormholes in the galactic halo region. Importantly, the study reveals that these wormholes can exist with both normal matter and exotic matter.
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
B. Mishra, F. Md. Esmeili, Saibal Ray
Summary: This article introduces and analyzes cosmological models with an anisotropic variable parameter. Two different models are constructed and analyzed, providing physical plausibility of the models.
INDIAN JOURNAL OF PHYSICS
(2021)
