Article
Astronomy & Astrophysics
Chunshan Lin
Summary: This study presents a general covariant local field theory of the holographic dark energy model, showing that the low energy effective theory is the massive gravity theory with a scalar graviton having strong coupling at certain energy scale. The UV-IR correspondence in this model stems from the breakdown of the effective field theory at the energy scale.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Mohammad Ali Gorji, Hayato Motohashi, Shinji Mukohyama
Summary: In the context of scalar-tensor theories, stealth de Sitter solutions face issues of infinite strong coupling or gradient instability, which can be resolved by introducing a controlled detuning mechanism known as scordatura. This mechanism not only resolves the mentioned issues, but also ensures a well-defined quasi-static limit.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Abdolali Banihashemi, Nima Khosravi, Arman Shafieloo
Summary: A new critically emergent dark energy model (CEDE) is proposed, which is consistent with both Planck's CMB data and Riess et al.'s local Hubble constant measurements. The model suggests that dark energy emerges at a transition redshift, providing a possible explanation for the Hubble constant tension.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Alvaro de la Cruz Dombriz, Francisco Jose Maldonado Torralba, David F. Mota
Summary: The stable pseudo-scalar degree of freedom in the quadratic Poincare Gauge theory of gravity is identified as a suitable candidate for dark matter. The study determines the parameter space in the theory that can explain all predicted cold dark matter phenomena and constrains these parameters with astrophysical observations.
Article
Astronomy & Astrophysics
Andreas Lymperis
Summary: By investigating the features of a non-metricity scalar Q function, the cosmological implications of f(Q) gravity are explored, and analytical expressions for the dark energy density, equation-of-state, and deceleration parameters are obtained. The study reveals that even in the absence of a cosmological constant, the universe follows the usual thermal history with matter and dark energy eras, and the dark energy equation-of-state parameter remains in the phantom regime. Additionally, the scenario shows excellent agreement with observational data from Supernovae type Ia. Furthermore, it is demonstrated that f(Q) gravity can effectively mimic the behavior of a cosmological constant.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Antonio De Felice, Shinji Mukohyama
Summary: This paper introduces a new cosmological framework integrating dark matter into a minimally modified gravity model, maintaining the same number of gravitational degrees of freedom through a series of transformations. The framework includes two time-dependent free functions to achieve desired evolutions of Hubble expansion rate and effective gravitational constant for dark matter.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Mauricio Reyes, Celia Escamilla-Rivera
Summary: This work presents an improvement on Gaussian reconstruction of the Hubble parameter data and explores new constraints in the Horndeski theory of gravity. The research finds that the prior used to calibrate the Pantheon supernovae data significantly affects the reconstructions, with the best fit reconstruction calibrated using the Ho value from The Carnegie-Chicago Hubble Program.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Celia Escamilla-Rivera, Antonio Najera
Summary: The study shows that certain dark energy parametrization models are ruled out and a strong preference against the Chevallier-Polarski-Linder model. A mock GW catalogue suggests that approximately 1000 standard sirens are needed to constrain H-0 within a 1% relative error.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Yuewei Wen, Eva Nesbit, Dragan Huterer, Scott Watson
Summary: Standard cosmological data analyses can't easily determine the presence of modified gravity. This study presents a quantitative mapping showing how modified gravity models appear within standard analyses, reporting specific biases in standard-parameter spaces. The implications for measurements of mass fluctuations are also discussed.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Daniele Oriti, Xiankai Pang
Summary: The analysis of emergent cosmological dynamics in mean field hydrodynamics of quantum gravity condensates reveals accelerated expansion of the universe at both early and late times. Although it does not support a compelling inflationary scenario in the early universe, it naturally produces a phantom-like dark energy dynamics at late times, which crosses the phantom divide and avoids any Big Rip singularity, approaching a de Sitter universe asymptotically.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Particles & Fields
Armin van de Venn, David Vasak, Johannes Kirsch, Juergen Struckmeier
Summary: The paper investigates the implications of metric compatible covariant canonical gauge theory of gravity on cosmological scales. The resulting equations of motion in a Friedmann-Lemaitre-Robertson-Walker Universe are derived for a totally anti-symmetric torsion tensor. The modifications of the Friedmann equations, equivalent to spatial curvature, are shown in the limit of a vanishing quadratic Riemann-Cartan term and are further investigated in the early and late times of the Universe's history.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Claudia de Rham, Scott Melville, Johannes Noller
Summary: Positivity bounds have been used to constrain scalar-tensor theories of dark energy, but coupling to matter fields has played a limited role. Demanding positivity when including interactions with standard matter fields leads to further constraints on the dark energy parameter space. Implementing these bounds as theoretical priors affects cosmological parameter constraints and shows that gravitational waves must travel superluminally on cosmological backgrounds in a standard UV completion.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Hooman Davoudiasl, Peter B. Denton, David A. McGady
Summary: The conventional lore excludes fermionic dark matter with mass lighter than a few hundred electronvolts based on the Pauli exclusion principle. A new method is proposed in this paper which involves numerous quasi-degenerate species of fermions without couplings to the standard model to evade this bound. Gravitational interactions impose constraints from measurements at the LHC, cosmic rays, supernovae, and black hole spins and lifetimes, with a particular limit on the number of distinct species of particles being less than or around 10^62.
Article
Astronomy & Astrophysics
Lilia Anguelova, John Dumancic, Richard Gass, L. C. R. Wijewardhana
Summary: This study presents an exact solution for the equations of motion of a two-field cosmological model, demonstrating the possibility of multi-field dark energy. The results show that even when the scalar potential maintains the rotational invariance of the field-space metric, it is still possible to have field-space trajectories that lead to accelerated space-time expansion.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Multidisciplinary
E. H. Baffou, M. J. S. Houndjo, I. G. Salako, F. K. Ahloui, A. D. Kanfon
Summary: In this paper, the Ricci dark energy model (RDE) with bulk viscosity is investigated in the context of f(R, T) gravity to explain the universe's accelerated expansion. By assuming that the cosmological evolution is governed by the RDE model with bulk viscosity, the modified Friedmann equations in flat geometry are derived from f(R, T) gravity. For a specific form of f(R, T) = R + 2AT model and a bulk viscosity coefficient of the form ξ = ξ0+ξ1H, various cosmological parameters such as the Hubble parameter, deceleration parameter, effective equation of state, statefinder, and Om diagnostic parameters are calculated. The results suggest that this model can be considered as an alternative candidate to describe dark energy.
CHINESE JOURNAL OF PHYSICS
(2023)
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)
Correction
Physics, Particles & Fields
Sanjar Shaymatov, Bobomurat Ahmedov, Mubasher Jamil
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.
