Article
Astronomy & Astrophysics
Umesh Kumar Sharma, Gunjan Varshney, Vipin Chandra Dubey
Summary: The study introduces a new dark energy model based on Barrow entropy and the holographic principle, using a time scale as an IR cut-off. By analyzing conformal time and the universe's age as infrared cut-offs, the cosmological significance of the suggested DE models is explored. The proposed models exhibit adequate nature in terms of equation of state, deceleration, and density parameters, potentially explaining late-time acceleration.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2021)
Article
Astronomy & Astrophysics
Pankaj, Bramha Dutta Pandey, P. Suresh Kumar, Umesh Kumar Sharma
Summary: This paper presents a model for studying the nature of dark energy using nonextensive Tsallis entropy. The model is based on the Karolyhazy relation, which combines ideas from quantum physics and general relativity. The agegraphic dark energy (ADE) models are proposed to explain the energy density of quantum fluctuations in spacetime. The study examines the cosmological implications of the hypothesized dark energy model, considering the expansion of the universe and the flow of energy between the dark matter and dark energy sectors.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2022)
Article
Physics, Particles & Fields
H. Garcia-Compean, D. Mata-Pacheco
Summary: This study investigates the Wheeler-DeWitt equation for a Kantowski-Sachs metric in Horava-Lifshitz gravity with a set of coordinates in minisuperspace that adhere to a generalized uncertainty principle. The equation is analyzed using both coordinates that adhere to the usual uncertainty principle and coordinates that adhere to the generalized uncertainty principle. Analytic solutions are found in the infrared region as well as a particular ultraviolet limit. The study reveals the possibility of oscillatory behavior in this context, but it is not a general feature for all parameter values.
Article
Physics, Mathematical
Ajitesh Kumar, Vandna Srivastava, Vipin Chandra Dubey, Umesh Kumar Sharma
Summary: By utilizing a Barrow entropy and the standard holographic method within a cosmic framework, we propose the Barrow agegraphic dark energy (BADE) model which incorporates the Universe age as an infrared cutoff scale in a flat FLRW Universe. The trajectories of the BADE model have been plotted in the (r,s) and (r,q) planes, revealing that the model exhibits characteristics of both Chaplygin gas and quintessence for various values of delta. Additionally, we examined the BADE model without interaction in the (omega(D),omega'(D)) plane, utilizing the observational data from Planck 2018 results for VI-lambda CDM and obtaining a dynamic study with the energy density BADE parameter omega(0)(D) = 0.70 and H-0 = 67.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2023)
Article
Astronomy & Astrophysics
Paul Martens, Hiroki Matsui, Shinji Mukohyama
Summary: In this paper, we introduce a well-tempered DeWitt wave function that vanishes at the classical big-bang singularity in Horava-Lifshitz (HL) cosmology. Through analytical and numerical methods, we demonstrate that in HL gravity, the DeWitt wave function for tensor perturbation is well-defined at the singularity and behaves well up to the finite size of the Universe.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Sheykhi, S. Ghaffari
Summary: In this study, the agegraphic dark energy (ADE) model is revisited, taking into account the entropy associated with the apparent horizon in the form of Barrow entropy. The modified model can successfully describe the transition from the early decelerated phase to the late-time accelerated phase in cosmology, and the evolution of cosmological parameters can be influenced by adjusting the Barrow exponent delta.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Kyungmin Kim, John J. Oh, Chan Park, Edwin J. Son
Summary: The study revealed that neutron stars (NSs) with larger radii and heavier masses in Ho.rava-Lifshitz (HL) gravity remain stable without collapsing into black holes, showing a deviation from general relativity (GR) can change the typical features of NS structure.
Article
Astronomy & Astrophysics
Ewa Czuchry
Summary: The standard ΛCDM model has unresolved issues like the initial singularity, which require modifications to general relativity. However, the Horava-Lifshitz theory offers an alternative with a bounce of the universe instead of an initial singularity. This review discusses previous works on the stability of this bounce in different formulations of the HL theory.
Article
Physics, Mathematical
Abdul Jawad, Shamaila Rani, Sameen Ashraf, Nadeem Azhar
Summary: We discuss the cosmological implications of the interacting Barrow holographic dark energy model in the context of flat deformed Horava-Lifshitz gravity by assuming the interaction between dark energy and pressureless dark matter. We investigate the evolutionary history of cosmological parameters and find results that favor observational data of Planck 2018. Moreover, we examine the generalized second law of thermodynamics of this cosmological system with barrow entropy as horizon entropy and observe that this law holds for both horizons.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Astronomy & Astrophysics
Phillipo Lappicy, Victor Hugo Daniel
Summary: We consider spatially homogeneous models in Horava-Lifshitz gravity and investigate the behavior of the induced Kasner map. We prove that for a certain range of parameters, the modified HL gravity models can lead to chaotic Kasner map despite its multi-valued nature in the subcritical regime.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Multidisciplinary Sciences
Abdul Jawad, Abdul Malik Sultan, Shamaila Rani
Summary: In this study, the matter-antimatter imbalance in the universe is investigated through baryogenesis, which is a physical process occurring after the big bang and resulting in an excess of matter over antimatter. The reproduction of the baryon to entropy ratio in the presence of modified Ho.rava-Lifshitz gravity is examined, considering different baryogenesis interactions proportional to (R) over tilde. Two models are analyzed with different values of F((R) over tilde). The results show that the matter-antimatter asymmetry is not eliminated by the modified gravity theory, indicating a consistent gravitational baryogenesis with recent observational data.
Article
Astronomy & Astrophysics
Kevin E. M. Church, Olivier Henot, Phillipo Lappicy, Jean-Philippe Lessard, Hauke Sprink
Summary: This passage discusses the spatially homogeneous Horava-Lifshitz models perturbing General Relativity by a parameter v in the interval (0, 1), where GR is recovered at v = 1/2. The author describes the dynamics for the extreme case v = 0, revealing new periodic orbit patterns distinct from the bouncing Kasner-like states predicted by the BKL picture.
GENERAL RELATIVITY AND GRAVITATION
(2023)
Article
Physics, Particles & Fields
Hongbo Cheng
Summary: This study investigates the Casimir force for parallel plates at finite temperature in the Horava-Lifshitz (HL) theory. It is found that the HL exponent cannot be chosen as an integer, otherwise the Casimir energy will be a constant, resulting in the disappearance of Casimir force between two parallel plates. Higher temperature weakens the attractive Casimir force, which is consistent with previous theoretical and experimental results. By appropriately selecting the HL factor, a thermally revised Casimir force similar to the standard results for parallel plates can be obtained.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Pameli Saha, Sayani Maity, Ujjal Debnath
Summary: This study investigates the newly approached extended f(P) cubic gravity in a cosmological background. Different types of dark energy candidates are examined and their cosmological nature is analyzed. Reconstructions of f(P) gravity models are studied based on various dark energy candidates, and their trajectories and stability conditions are analyzed.
MODERN PHYSICS LETTERS A
(2022)
Article
Physics, Multidisciplinary
Ahmad Sheykhi, Maral Sahebi Hamedan
Summary: The thermodynamics-gravity conjecture suggests a strong connection between the gravitational field equations and the first law of thermodynamics, meaning any changes in entropy expression directly impact the field equations. By considering the modified Barrow entropy associated with the apparent horizon, the Friedmann equations are altered as well. This paper explores the implications of this modification on the holographic dark energy (HDE) model, highlighting changes in energy density and the Friedmann equations. The study also investigates the cosmological consequences of using the Hubble horizon and future event horizon as infrared cutoffs, including interactions between dark matter (DM) and dark energy (DE), and the impact of the Barrow exponent on the cosmological behavior of HDE, such as crossing the phantom line and shifting the universe phase transition time.
Article
Physics, Nuclear
Sen Yang, Cheng Liu, Tao Zhu, Li Zhao, Qiang Wu, Ke Yang, Mubasher Jamil
Summary: This study investigates the spherical accretion flow onto general parametrized spherically symmetric black hole spacetimes, analyzing the accretion process for various perfect fluids. The influences of additional parameters beyond the Schwarzschild black hole on flow behavior are studied in detail, as well as the accretion of the ideal photon gas and its correspondence with the photon sphere for general parameterized spherically symmetric black holes. Possible extensions of the analysis are also discussed.
Article
Physics, Particles & Fields
Javlon Rayimbaev, Ahmadjon Abdujabbarov, Mubasher Jamil, Wen-Biao Han
Summary: This study investigates the effects of Einstein-(Ether gravity on magnetized particles orbiting a black hole immersed in a magnetic field, exploring the impact of free parameters on particle trajectories, innermost stable circular orbits, and collision energy. The study also compares these effects with those of rotating Kerr black holes, finding similar behavior for certain values. Additionally, the cases where a static /Ether black hole can be described as a Schwarzschild black hole in modified gravity are analyzed with corresponding parameter values.
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)
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
Astronomy & Astrophysics
Mohammad Sadeghi, Karam Bahari, Kayoomars Karami
Summary: Observations indicate the existence of twisted magnetic flux tubes and plasma flow in the solar atmosphere. The goal of this study is to determine the damping rate of sausage modes in the presence of magnetic twist and plasma flow. By numerically solving the dispersion relation for sausage modes in a non-uniform layer with magnetic pores under the condition of slow continuity, we find that the effect of twisted magnetic field on resonance absorption is greater for low speed plasma flow than for high speed.
ASTROPHYSICAL JOURNAL
(2023)
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.