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We use WMAP5 and other cosmological data to constrain model parameters in quintessence cosmologies, focusing also on their shift when we allow for non-vanishing neutrino masses. The Ratra-Peebles (RP) and SUGRA potentials are used here, as…

宇宙学与河外天体物理 · 物理学 2010-05-28 G. La Vacca , J. R. Kristiansen

We investigated evolution of metric and density perturbations for Tsallis model of holographic dark energy with energy density $\sim L^{2\gamma - 4}$, where $L$ is length of event horizon or inverse Hubble parameter and $\gamma$ is…

广义相对论与量子宇宙学 · 物理学 2025-08-25 Artyom V. Astashenok , Alexander S. Tepliakov

In this paper, a well-motivated parametrization of the Hubble parameter ($H$% ) is revisited that renders two models of dark energy showing some intriguing features of the late-time accelerating Universe. A general quintessence field is…

广义相对论与量子宇宙学 · 物理学 2023-09-19 Amine Bouali , Himanshu Chaudhary , Amritansh Mehrotra , S. K. J. Pacif

In this paper we study the evolution of the dark energy parameter within the scope of a spatially homogeneous and isotropic Friedmann-Robertson-Walker (FRW) model filled with barotropic fluid and dark energy by revisiting the recent results…

广义相对论与量子宇宙学 · 物理学 2015-05-01 Bijan Saha , Hassan Amirhashchi , Anirudh Pradhan

The current paper provides a comprehensive examination of a dark energy cosmological model in the classical regime, in which a generic scalar field is regarded as a dark energy source. Einstein's field equations are solved in model…

广义相对论与量子宇宙学 · 物理学 2022-09-07 Ritika Nagpal , Shibesh Kumar Jas Pacif , Abhishek Parida

In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein's cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a…

广义相对论与量子宇宙学 · 物理学 2019-11-22 S. K. J. Pacif , Md Salahuddin Khan , L. K. Paikroy , Shalini Singh

We investigate the cosmological implications of Tsallis entropy in two widely discussed frameworks: the Cai-Kim thermodynamic derivation of the Friedman equations and the Tsallis holographic dark energy (HDE) scenario, considering both the…

Motivated by the holographic principle, it has been suggested that the dark energy density may be inversely proportional to the area $A$ of the event horizon of the universe. However, such a model would have a causality problem. In this…

广义相对论与量子宇宙学 · 物理学 2012-06-06 Antonio Pasqua , A. Khodam-Mohammadi , Mubasher Jamil , R. Myrzakulov

It is demonstrated that entropy and its density play a significant role in solving the problem of the vacuum energy density (cosmological constant) of the Universe and hence the dark energy problem. Taking this in mind, two most popular…

广义相对论与量子宇宙学 · 物理学 2011-04-07 A. E. Shalyt-Margolin

A six parameter cosmological model, involving a vacuum energy density that is extremely tiny compared to fundamental particle physics scales, describes a large body of increasingly accurate astronomical data. In a first part of this brief…

高能物理 - 唯象学 · 物理学 2009-11-11 Norbert Straumann

By considering the logarithmic correction to the energy density, we study the behavior of Hubble parameter in the holographic dark energy model. We assume that the universe is dominated by interacting dark energy and matter and the…

综合物理 · 物理学 2011-05-09 H. Mohseni Sadjadi , Mubasher Jamil

We investigate Kaniadakis-holographic dark energy by confronting it with observations. We perform a Markov Chain Monte Carlo analysis using cosmic chronometers, supernovae type Ia, and Baryon Acoustic Oscillations data. Concerning the…

Entropy bounds render quantum corrections to the cosmological constant $\Lambda$ finite. Under certain assumptions, the natural value of $\Lambda$ is of order the observed dark energy density $\sim 10^{-10} {\rm eV}^4$, thereby resolving…

高能物理 - 理论 · 物理学 2008-11-26 Stephen D. H. Hsu

Are geometrical summaries of the CMB and LSS sufficient for estimating cosmological parameters? And how does our choice of a dark energy model impact the current constraints on standard cosmological parameters? We address these questions in…

宇宙学与河外天体物理 · 物理学 2009-03-17 Rahul Biswas , Benjamin D. Wandelt

We study the cosmological consequences of interacting Tsallis holographic dark energy model in the framework of the fractal universe, in which, the Hubble radius is considered as the IR cut-off. We drive the equation of state (EoS)…

广义相对论与量子宇宙学 · 物理学 2020-06-24 S. Ghaffari , E. Sadri , A. H. Ziaie

We investigate the cosmological implications of entropy-based approaches in the context of Holographic Dark Energy (HDE) and Gravity-Thermodynamics (GT) formalisms. We utilise the extended Barrow entropy form, with the index parameter…

宇宙学与河外天体物理 · 物理学 2025-04-16 Udit K. Tyagi , Sandeep Haridasu , Soumen Basak

Current observational bounds on dark energy depend on assumptions about the curvature of the universe. We present a simple and efficient method for incorporating constraints from CMB anisotropy data, and use it to derive constraints on…

天体物理学 · 物理学 2010-04-06 Yun Wang , Pia Mukherjee

Tsallis entropy is a generalization of the Boltzmann-Gibbs entropy in statistical theory which uses a parameter $\delta$ to measure the deviation from the standard scenario quantitatively. Using concepts of Tsallis entropy and future event…

综合物理 · 物理学 2022-04-19 Bramha Dutta Pandey , Suresh Kumar P , Pankaj , Umesh Kumar Sharma

We investigate a spatially flat Friedmann-Robertson-Walker (FRW) cosmological model with cold dark matter coupled to a modified holographic Ricci dark energy through a general interaction term linear in the energy densities of dark matter…

广义相对论与量子宇宙学 · 物理学 2012-10-15 Luis P. Chimento , Mónica I. Forte , Martín G. Richarte

In this work, we have considered the flat FRW model of the universe in $(n+2)$-dimensions filled with the dark matter (perfect fluid with negligible pressure) and the modified Chaplygin gas (MCG) type dark energy. We present the Hubble…

综合物理 · 物理学 2015-09-09 Chayan Ranjit , Shuvendu Chakraborty , Ujjal Debnath