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
S. Smerechynskyi, M. Tsizh, B. Novosyadlyj
Summary: The study investigates the density distribution of minimally-coupled scalar field dark energy inside a neutron star and its impact on the mass limit. The effective speed of sound of dark energy is found to be not smaller than approximately 10^(-2) in units of squared speed of light.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Farida Bargach, Aatifa Bargach, Mariam Bouhmadi-Lopez, Ahmed Errahmani, Taoufik Ouali
Summary: This paper presents a dynamical system analysis of a holographic dark energy model based on a modified theory of gravity in a braneworld scenario. The study considers different infra-red cutoffs for the holographic dark energy and analyzes the critical points, stability, and late-time cosmological viability of the solutions in the phase space. The analysis extends to investigating noninteracting and interacting cases between dark energy and cold dark matter in specific forms of interaction.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2021)
Article
Astronomy & Astrophysics
Mohit Kumar Sharma, Sourav Sur
Summary: We analyze the dynamical system of interacting dark energy-matter scenarios and study the critical points and stability at both the background level and the level of density perturbations. We find a double degeneracy in the critical point spectrum in the inhomogeneous picture due to the possible growth and decay of matter density perturbations. By analyzing the dynamics of the growth factor, we show that it initially surpasses unity at one of the critical points and leads to a stable configuration as the matter density fluctuations diminish. As for the growth index, we find that the only physically plausible trajectory is one that evolves mildly at high redshifts and becomes steeper with time, with an average value close to 6/11.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Alexander Ganz
Summary: Minimally modified gravity models use auxiliary constraints to maintain a dynamic cosmological background, with results of linear perturbations being insensitive to constraint details, leading to a modified effective gravitational constant or a non-zero dust sound speed.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Norman Cruz, Gabriel Gomez, Esteban Gonzalez, Guillermo Palma, Angel Rincon
Summary: This paper combines the running vacuum model and viscous dark matter scenarios in a cosmological setting and studies their implications. Through dynamical system analysis and numerical exploration, the authors find that the phase space of the combined models exhibits characteristics different from the single scenarios.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Weiqiang Yang, Eleonora Di Valentino, Supriya Pan, Yabo Wu, Jianbo Lu
Summary: This article compares various dynamical dark energy models using different observational data and discusses the alleviation of H-0 tension. Bayesian evidence analysis shows that all models perform better than Lambda CDM scenario, with the CPL model being the best in fitting the data and solving H-0 tension. However, the tension reappears when considering the baryon acoustic oscillations data, not supporting the dynamical dark energy solution.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Eoin O. Colgain, M. M. Sheikh-Jabbari, Lu Yin
Summary: The study demonstrates that parametric models of dynamical dark energy have a degree of arbitrariness, with errors in wa being sensitive to different redshift functions f(z). Additionally, classic DDE models such as the Chevallier-Polarski-Linder model are less sensitive to DDE, while wiggles uncovered in nonparametric reconstructions require a thorough analysis of correlations.
Article
Astronomy & Astrophysics
Yan-Hong Yao, Xin-He Meng
Summary: The H0 tension between low- and high-redshift measurements is a serious issue. To address this, the authors propose a new interacting dark energy model with a time-varying coupling parameter. They parameterize the densities of dark matter and dark energy, and their findings suggest a correlation between the parameter and the Hubble constant.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Roberto C. Blanquet-Jaramillo, Roberto A. Sussman, Maximo A. Aguero Granados, German Izquierdo
Summary: In this paper, we investigate inhomogeneous spherically symmetric models based on the LTB metric, considering an interactive mixture of ordinary baryonic matter, cold dark matter, and dark energy. We analyze the evolution of energy density and spatial curvature profiles using projection methods and study the critical points of the system. Numerical solutions are also obtained for initial energy density and curvature profiles leading to a spherical bounce.
MODERN PHYSICS LETTERS A
(2022)
Article
Astronomy & Astrophysics
Yourong Wang, Richard Easther
Summary: In this study, we simulated the gravitational dynamics between a massive object and ultralight/fuzzy dark matter. The results showed gravitational collapse induced by a moving mass in a uniform medium, as well as coherent breathing modes in the dark matter caused by a large moving point mass.
Article
Astronomy & Astrophysics
Srijita Sinha, Manisha Banerjee, Sudipta Das
Summary: In this paper, an interacting model of dark energy was examined, where the dark sectors are allowed to interact among themselves through an assumed relation. By solving the perturbation equations numerically, the imprints on the growth of matter and dark energy fluctuations were studied. It was observed that higher rates of interaction strength for the coupling term resulted in visible imprints on the dark energy density fluctuations at the early epochs of evolution.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Safae Dahmani, Amine Bouali, Imad El Bojaddaini, Ahmed Errahmani, Taoufik Ouali
Summary: The discrepancy between Planck data and direct measurements of H0 and S8 has become one of the most intriguing puzzles in cosmology. The tension in H0 has reached 5σ in the context of the standard cosmology model. Exploring physics beyond the standard model is necessary to explain this issue.
PHYSICS OF THE DARK UNIVERSE
(2023)
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
Physics, Nuclear
Vishnu Jejjala, Michael J. Kavic, Djordje Minic, Tatsu Takeuchi
Summary: This paper argues that a mixing between infrared and ultraviolet degrees of freedom in quantum gravity leads to infinite statistics, which is consistent with Lorentz invariance in the presence of nonlocality, and results in a fine structure for dark energy. By introducing infrared and ultraviolet cutoffs into the quantum gravity action, the form of A as a function of redshift is deduced and translated into the behavior of the Hubble parameter.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2022)
Article
Physics, Particles & Fields
Mohammad R. Garousi, Hanif Golchin
Article
Physics, Particles & Fields
Hanif Golchin, Ahmad Ghodsi, M. M. Sheikh-Jabbari
JOURNAL OF HIGH ENERGY PHYSICS
(2013)
Article
Physics, Particles & Fields
Ahmad Ghodsi, Hanif Golchin, M. M. Sheikh-Jabbari
JOURNAL OF HIGH ENERGY PHYSICS
(2014)
Article
Physics, Particles & Fields
Hanif Golchin, Mohammad Reza Mehdizadeh
EUROPEAN PHYSICAL JOURNAL C
(2019)
Article
Physics, Particles & Fields
Hanif Golchin
JOURNAL OF HIGH ENERGY PHYSICS
(2020)
Article
Astronomy & Astrophysics
Hanif Golchin
Summary: In this paper, we investigate the entropy products of inner and outer horizons for different types of regular black hole solutions. We find that the universality of the entropy product, similar to singular black holes, holds for some regular solutions but fails for others. By using the thermodynamics method introduced by Chen et al. (J. High Energy Phys. 03 (2013) 102), we read the central charges of the dual CFTs from the entropy product for the regular black holes that respect the universality. We also calculate the central charges using the asymptotic symmetry group formalism, and the results of both approaches are consistent, indicating that the universality of the entropy product provides a simple method for finding the central charges of the dual CFTs.
Article
Astronomy & Astrophysics
Hanif Golchin