Article
Astronomy & Astrophysics
Muhammad F. A. R. Sakti, Anto Sulaksono
Summary: The researcher constructed an exact star solution of a dark energy star, analyzed its energy conditions, and found that it may violate the strong energy condition under specific circumstances. The study also discovered stability issues in terms of convective motion and gravitational cracking for the dark energy star.
Article
Astronomy & Astrophysics
Xiang-Qian Li, Hao-Peng Yan, Li-Li Xing, Shi-Wei Zhou
Summary: A static spherically symmetric black hole solution is obtained for the Einstein gravitational equations in the presence of a Chaplygin-like dark fluid. The black hole exhibits a small/large phase transition similar to the van der Waals system in the extended phase space. Additionally, the low-/high-phi phase transition of the black hole in the nonextended phase space is studied, and the critical exponents and scaling behavior of thermodynamic quantities near criticality are derived. The "shadow thermodynamics" of AdS black holes surrounded by the Chaplygin-like dark fluid is also investigated, revealing a positive correlation between the shadow radius and the event horizon radius.
Article
Physics, Multidisciplinary
Xiang-Qian Li, Bo Chen, Li-Li Xing
Summary: In this study, we investigated black hole solutions in the presence of modified Chaplygin gas as a cosmic background, and found that the spacetime structure could be either asymptotically anti-de Sitter or de Sitter. For asymptotically anti-de Sitter black hole, we observed small/large black hole phase transition, while for asymptotically de Sitter black hole, there was no criticality or phase transition.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Astronomy & Astrophysics
Nandan Roy, Sangita Goswami, Sudipta Das
Summary: This study proposes a simple parametrization scheme for the Hubble parameter that can be applied to scalar field dark energy models. The proposed scheme allows for the incorporation of both quintessence and phantom scalar field, and provides cosmological parameters independent of the nature of the scalar field. The study finds that observational data prefers the equation of state for dark energy to be in the phantom domain.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
Joaquin Estevez-Delgado, Modesto Pineda Duran, Arthur Cleary-Balderas, Noel Enrique Rodriguez Maya, Jose Martinez Pena
Summary: This study presents a stellar model formed by ordinary and quintessence matter with anisotropic pressures, satisfying physical and potentially stable conditions. Graphic representations show the behavior of the solution for a specific mass and radius corresponding to the star EXO 1785-248.
MODERN PHYSICS LETTERS A
(2021)
Article
Physics, Particles & Fields
Jackie C. H. Liu
Summary: Based on the ratio gravity theory, we propose a mechanism to generate dynamical dark energy by coupling gravity with a quintessence field. This model leads to different behaviors of dark energy in the early and late universe, with the quintessence field starting as a constant and oscillating as the universe expands.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Aroonkumar Beesham, Mfanafuthi Siyabonga Msweli
Summary: Dark energy is believed to make up the majority of matter in the universe, and its nature remains poorly understood despite efforts to explain it. This presentation examines the relationship between two potential forms of dark energy, Chaplygin gas and bulk viscosity, and finds that they are mathematically equivalent but differ in their physical interpretation.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2022)
Article
Multidisciplinary Sciences
Cosmin Andrei, Anna Ijjas, Paul J. Steinhardt
Summary: In this paper, we investigate how short the remaining period of expansion can be given current observational constraints on dark energy, and discuss how this scenario fits naturally with cyclic cosmologies and recent conjectures about quantum gravity.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Physics, Multidisciplinary
Juerg Froehlich
Summary: This article presents a unified model of "dark matter" and discusses its implications for the late-time evolution of the universe and the matter-antimatter asymmetry.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Astronomy & Astrophysics
Daris Samart, Bhuddhanubhap Silasan, Phongpichit Channuie
Summary: This study investigates the dynamics of interacting dark energy and dark matter in viable models of f(R) gravity using a standard framework of dynamical system analysis. The results show that in models with this interaction, the dynamical profiles of the Universe in viable f(R) dark energy models are modified by the interaction term and relevant model parameters. Additionally, the correct cosmological evolution with additional constraint parameter, alpha, from the interacting dark energy is obtained.
Article
Astronomy & Astrophysics
Vitor da Fonseca, Tiago Barreiro, Nelson J. Nunes
Summary: In this study, a quintessence model is constructed where the scalar field has a linear dependence on the number of e-folds. The proposed parametrisation conveniently constrains the evolution of the dark energy equation of state and also considers a non-minimal coupling to cold dark matter. Analysis of observational data indicates a non-vanishing coupling with energy transfer from dark energy to dark matter preferred by CMB measurements.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
Gongjun Choi, Weikang Lin, Luca Visinelli, Tsutomu T. Yanagida
Summary: Using the reported non-zero rotation angle of the cosmic microwave background (CMB) linear polarization as a hint, a new model for quintessence dark energy is proposed and speculated based on experimental results, aiming to predict the equation of state of dark energy and distinguish it from the cosmological constant for future testing.
Article
Astronomy & Astrophysics
Yashar Akrami, Misao Sasaki, Adam R. Solomon, Valeri Vardanyan
Summary: Models of dark energy with multiple fields are theoretically motivated and predict distinct observational signatures, potentially addressing issues present in standard single-field dark energy. While these multi-field models may appear similar to concordance cosmology at the background level, dark energy perturbations can cluster and enhance the growth of large-scale structure, which may be testable in future cosmological surveys.
Article
Astronomy & Astrophysics
William J. Wolf, Pedro G. Ferreira
Summary: Compelling evidence suggests that the Universe is in a late phase of accelerated expansion, possibly due to the existence of dark energy. Numerous microphysical models for dark energy have been proposed, with the hope of precisely identifying the model through increasingly precise cosmological surveys. However, it is argued that this is unlikely and at best, we can only have a phenomenological description of the microphysics of dark energy. Furthermore, it is suggested that the current phenomenological prescriptions are not equipped to reveal the fundamental theory of dark energy.
Article
Astronomy & Astrophysics
Rodrigo von Marttens, Dinorah Barbosa, Jailson Alcaniz
Summary: Einstein's equations connect the space-time geometry to the total matter content of the cosmic substratum, but not to individual contributions of the matter species. Therefore, it is difficult to differentiate cases where dark energy interacts with dark matter from a non-interacting scenario using observational data based on time or distance measurements.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Sourabh Nampalliwar, Saurabh Kumar, Kimet Jusufi, Qiang Wu, Mubasher Jamil, Paolo Salucci
Summary: This paper investigates the impact of a dark matter spike on the vicinity of the black hole Sgr A* in the center of the Milky Way. The study examines the influence of dark matter density on the shadow radius and image of the black hole, concluding that the effect is weak for realistic densities but may become significant at higher densities near the black hole. However, simulations with radio interferometry, similar to an EHT array, suggest that detecting this effect in the near future is unlikely.
ASTROPHYSICAL JOURNAL
(2021)
Article
Physics, Particles & Fields
Javlon Rayimbaev, Sanjar Shaymatov, Mubasher Jamil
Summary: This paper investigates circular orbits around a black hole surrounded by dark matter, showing how dark matter impacts the existence of circular orbits and exploring its applications in fitting and explaining black hole parameters.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Correction
Physics, Particles & Fields
Sanjar Shaymatov, Bobomurat Ahmedov, Mubasher Jamil
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
Sanjar Shaymatov, Bobomurat Ahmedov, Mubasher Jamil
Summary: This study tests the weak cosmic censorship conjecture for the Reissner-Nordstrom-de Sitter black hole surrounded by perfect fluid dark matter, showing that even in a realistic scenario with cosmological parameters, the black hole cannot be overcharged unless the induced fields by dark matter and cosmological parameters are completely balanced. Additionally, it is found that a certain threshold limit exists beyond which the black hole cannot be overcharged, indicating that the effect of the cosmological constant dominates over the effect of perfect fluid dark matter in the overcharging process.
EUROPEAN PHYSICAL JOURNAL C
(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
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, 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, Particles & Fields
Kimet Jusufi, Salvatore Capozziello, Sebastian Bahamonde, Mubasher Jamil
Summary: We use observational data to constrain a black hole solution of extended teleparallel gravity models based on the S2 star orbiting the Galactic Center. We construct the shadow images of the Sgr A* black hole and find that the shadow radius increases with the parameter alpha. The observables, such as the deflection angle and angular diameter, are close to the Schwarzschild case. However, the electromagnetic intensity observed in the shadow images is smaller compared to General Relativity (GR), indicating differences in the Born-Infeld f(T) gravity.
EUROPEAN PHYSICAL JOURNAL C
(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)
Article
Astronomy & Astrophysics
Farruh Atamurotov, Kimet Jusufi, Mubasher Jamil, Ahmadjon Abdujabbarov, Mustapha Azreg-Ainou
Summary: This paper investigates the influence of axion-plasmon on the optical properties of Schwarzschild black hole. It is found that the size of the black hole shadow decreases with increasing axion-plasmon coupling, indicating changes in gravitational deflection angle and other properties.
Correction
Astronomy & Astrophysics
Cheng Liu, Tao Zhu, Qiang Wu, Kimet Jusufi, Mubasher Jamil, Mustapha Azreg-Ainou, Anzhong Wang