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The behavior of the dark energy equation of state (EOS) is crucial in distinguishing different cosmological models. With a model independent approach, we constrain the possible evolution of the dark energy EOS. Gamma-ray bursts (GRBs) of…

Astrophysics · Physics 2008-12-20 Shi Qi , Fa-Yin Wang , Tan Lu

We study the interaction between dark energy (DE) and dark matter (DM) in the scope of anisotropic bianchi type I space-time. First we derive the general form of the dark energy equation of state parameter (EoS) in both non-interacting and…

General Relativity and Quantum Cosmology · Physics 2015-06-19 Hassan Amirhashchi , S. N. A. Qazi , Hishamuddin Zainuddin

We study the holographic dark energy (HDE) model in generalized Brans-Dicke scenario with a non-minimal coupling between the scalar field and matter lagrangian namely Chameleon Brans Dicke (CBD) mechanism. In this study we consider the…

General Relativity and Quantum Cosmology · Physics 2014-07-02 K. Saaidi , H. Sheikhahmadi , T. Golanbari , S. W. Rabiei

In this study, we introduce a novel late-time effective dark energy model characterized by a quadratic equation of state (EoS) and rigorously examine its observational constraints. Initially, we delve into the background dynamics of this…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-11 Hossein Moshafi , Alireza Talebian , Ebrahim Yusofi , Eleonora Di Valentino

In this paper, we investigate the cosmological consequences of ghost dark energy model in modified Gauss-Bonnet gravity. We construct ghost dark energy $f(G)$ model by using correspondence scenario for both interacting and non-interacting…

General Relativity and Quantum Cosmology · Physics 2019-08-21 M. Sharif , Saadia Saba

In the background of a homogeneous and isotropic spacetime with zero spatial curvature, we consider interacting scenarios between two barotropic fluids, one is the pressureless dark matter (DM) and the other one is dark energy (DE), in…

General Relativity and Quantum Cosmology · Physics 2017-02-01 German S. Sharov , Subhra Bhattacharya , Supriya Pan , Rafael C. Nunes , Subenoy Chakraborty

In this paper I give a brief review on the recently proposed new scenario of dark energy model dubbed $Quintom$. Quintom describes the dynamical dark energy models where the equation of state getting across the cosmological constant…

Astrophysics · Physics 2007-05-23 Bo Feng

Dark energy cosmologies with an equation of state parameter $w$ less than -1 are often found to violate the null energy condition and show unstable behaviour. A solution to this problem may require the existence of a consistent effective…

High Energy Physics - Theory · Physics 2009-04-22 Ben M. Leith , Ishwaree P. Neupane

We study two transition periods in cosmology: radiation-to-matter and matter-to-dark energy. In each case, we define a new parameter $\chi$ given by the ratios of the two energy densities involved in the transition. Our study of the second…

General Relativity and Quantum Cosmology · Physics 2024-06-05 Bob Osano

This study explores the possibility of a time-varying dark energy (DE) equation of state (EoS) deviating from -1. We employ a comprehensive dataset of usual astronomical probes (Type Ia supernovae, baryon acoustic oscillations, Big Bang…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-23 Mehdi Rezaei , Supriya Pan , Weiqiang Yang , David F. Mota

Recent cosmological observations, including DESI Data Release 2 (DR2) \cite{DESIDR2}, allow for mild redshift evolution of the dark energy equation of state (EoS), motivating renewed interest in the phantom regime ($w<-1$). A no-go result…

General Relativity and Quantum Cosmology · Physics 2026-02-03 Prasanta Sahoo

Several independent cosmological data, collected within the last twenty years, revealed the accelerated expansion rate of the Universe, usually assumed to be driven by the so called dark energy, which, according to recent estimates,…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-16 Marek Demianski , Elisabeta Lusso , Maurizio Paolillo , Ester Piedipalumbo , Guido Risaliti

We propose and investigate a class of dynamical dark energy models in which the cosmological constant evolves from negative values in the early Universe to a positive value at low redshifts. This framework includes a generalised ladder-step…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-20 Mariam Bouhmadi-López , Beñat Ibarra-Uriondo

We conduct a Bayesian analysis of recent observational datasets, specifically the Cosmic Chronometers (CC) dataset and Pantheon samples, to investigate the evolution of the EoS parameter in dark energy models. Our study focused on the…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-29 N. Myrzakulov , M. Koussour , Alnadhief H. A. Alfedeel , Amare Abebe

Recent analysis of the DESI Collaboration challenges the $\Lambda$-Cold Dark Matter ($\Lambda$CDM) model, suggesting evidence for a dynamic dark energy. These results are obtained in the context of generic parameterizations of the dark…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-21 Rayff de Souza , Gabriel Rodrigues , Jailson Alcaniz

In this paper, we study the new Tsallis agegraghic dark energy model in the context of fractal cosmology. The different cosmic implications such as statefinder diagnosis, cosmological plane and squared of sound speed in both interacting and…

General Relativity and Quantum Cosmology · Physics 2024-01-17 M. Abdollahi Zadeh

We have constructed a dark energy cosmological model in the framework of generalized Brans Dicke theory (GBD) with a self-interacting potential. The source of dark energy is considered through a unified dark fluid (UDF) characterized by a…

General Relativity and Quantum Cosmology · Physics 2024-03-21 S K Tripathy , A Sendha , S K Pradhan , Z. Naik , B. Mishra

We study cosmological models with interaction between dark energy (DE) and dark matter (DM). For the interaction term $Q$ in cosmic evolution equations, there is a model-independent degeneracy-breaking (D-B) point when $Q_{1}$ (a part of…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-20 Z. Zhou , T. J. Zhang , T. P. Li

We study the dynamics of expansion of the homogeneous isotropic Universe and the evolution of its components in the model with nonminimally coupled dynamical dark energy. Dark energy, like the other components of the Universe, is described…

General Relativity and Quantum Cosmology · Physics 2017-12-05 R. Neomenko , B. Novosyadlyj , O. Sergijenko

In this paper the accelerating expansion of our universe at the late cosmic evolution time in a generally modified (extended) \emph{Chaplygin gas} (Dark Fluid) model is detailed, which is characterized by two parameters ($m$, $\alpha$).…

Astrophysics · Physics 2007-05-23 Xin-He Meng , Ming-Guang Hu , Jie Ren
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