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The evolution of dark energy density is a crucial quantity in understanding the nature of dark energy. Often, the quantity is described by the so-called equation of state, that is the ratio of dark energy pressure to its density. In this…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-14 Ahmad Mehrabi , Maryam Vazirnia

We study dark energy through the viewpoints of parametric and nonparametric analyses of late-time cosmological data. We consider four Hubble parameter priors reflecting the Hubble tension and make use of two phenomenological functions,…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-27 Reginald Christian Bernardo , Daniela Grandón , Jackson Levi Said , Víctor H. Cárdenas

We present a model for the present accelerating Universe and focus on the different important physical variables involved in the model under the phenomenological assumption $\Lambda \propto H^2$ with a prescription for equation of state…

General Physics · Physics 2011-07-15 Saibal Ray , Farook Rahaman , Utpal Mukhopadhyay , Ruby Sarkar

Abandoning the perfect fluid hypothesis, we investigate here the possibility that the dark energy equation of state (EoS) $w$ is a nonlinear function of the energy density $\rho$. To this aim, we consider four different EoS describing…

Astrophysics · Physics 2009-11-13 V. F. Cardone , C. Tortora , A. Troisi , S. Capozziello

We present a novel dynamical dark energy model within the frameworks of both Einstein gravity and Horava-Lifshitz gravity. Utilizing CDMMA parametrization of the dark energy equation of state $\omega(z)$, we derive solutions to the field…

General Relativity and Quantum Cosmology · Physics 2024-11-26 Ujjal Debnath , Himanshu Chaudhary , Niyaz Uddin Molla , S. K. J. Pacif , G. Mustafa

The presented paper is a comprehensive analysis of two dark energy (DE) cosmological models wherein exact solutions of the Einstein field equations (EFEs) are obtained in a model-independent way (or by cosmological parametrization). A…

General Physics · Physics 2022-07-20 S. K. J. Pacif

We Consider a cosmological model based on a generalization of the equation of state proposed by Nojiri and Odintsov [46] and \v{S}tefan\v{c}i'c [47], [48]. We argue that this model works as a dark fluid model which can interpolate between…

General Relativity and Quantum Cosmology · Physics 2023-02-17 Esraa Elkhateeb

We investigate a generalized power-law dark energy equation of state of the form $p = w\rho - \beta\rho^m$ in a flat FLRW universe, analyzing its dynamical stability and thermodynamic consistency. The model exhibits a rich phase space…

General Relativity and Quantum Cosmology · Physics 2025-07-08 S. Kazemi , M. A. Ramzanpour , E. Yusofi , A. R. Amani

We present an updated and improved equation of state (which we call the NDL EoS) for use in neutron-star structure and supernova simulations. This EoS is based upon a framework originally developed by Bowers & Wilson, but there are numerous…

High Energy Astrophysical Phenomena · Physics 2013-03-04 Matthew Meixner , J. Pocahontas Olson , Grant Mathews , N. Q. Lan , H. E. Dalhed

As an alternative to the popular parametrisations of the dark energy equation of state, we construct a quintessence model where the scalar field has a linear dependence on the number of e-folds. Constraints on more complex models are…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-17 Vitor da Fonseca , Tiago Barreiro , Nelson J. Nunes

We investigate how strongly late-time inferences about DE dynamics depend on the functional prior used to represent the expansion history. Using identical late-time combinations of CC, DESI BAO measurements, the Pantheon+ SN1a sample, and…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-15 Özgür Akarsu , Maria Caruana , Konstantinos F. Dialektopoulos , Luis A. Escamilla , Emre O. Kahya , Jackson Levi Said

We present a new parameterization for the equation of state (EoS) $\omega_X=P_X/\rho_X$, which can reproduce a $f(R)$-like evolution with a precision between $[0.5\%-0.8\%]$ over the numerical solutions. Also, our proposal can render a…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-24 Luisa G. Jaime , Mariana Jaber , Celia Escamilla-Rivera

While cold dark matter is widely supported by a range of cosmological observations, it encounters several difficulties at smaller scales. These issues have prompted the investigation of various alternative dark matter candidates, leaving…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-23 Jian-Qi Liu , Yan-Hong Yao , Yan Su , Jia-Wei Wu

The dynamics of expansion and large scale structure formation in the multicomponent Universe with dark energy modeled by the minimally coupled scalar field with generalized linear barotropic equation of state (EoS) are analyzed. It is shown…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-09 B. Novosyadlyj , O. Sergijenko , S. Apunevych , V. Pelykh

We compare the maximal abundance of massive systems predicted in different dynamical dark energy (DDE) models at high redshifts z = 4-7 with the measured abundance of the most massive galaxies observed to be already in place at such…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-27 N. Menci , A. Grazian , M. Castellano , P. Santini , E. Giallongo , A. Lamastra , F. Fortuni , A. Fontana , E. Merlin , T. Wang , D. Elbaz , N. G. Sanchez

We present a theoretical study of an early dark energy (EDE) model. The equation of state $\omega(z)$ evolves during the thermal history in a framework of a Friedmann-Lemaitre-Robertson-Walker Universe, following an effective…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-17 Luz Ángela García , Leonardo Castañeda , Juan Manuel Tejeiro

We explore the cosmological evolution of equation of state (EoS) for dark energy in g-essence models, the action of which is described by a function of both the canonical kinetic term of both the scalar and fermionic fields. We examine…

General Physics · Physics 2013-05-06 Kazuharu Bamba , Olga Razina , Koblandy Yerzhanov , Ratbay Myrzakulov

We investigate the hypothesis that the evolution of the Universe can be described by a single dark fluid whose effective equation of state (EoS), $\omega_{\rm{eff}}$, is a linear combination of a logarithmic term and a power law term, both…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-30 Vipin Chandra Dubey , Subhajit Saha , Abdulla Al Mamon

This paper is a parametrization of the equation of state (EoS) parameter of dark energy (DE), which is parameterized using Square-Root (SR) form i.e. $\omega _{SR}=\text{$\omega _{0}$}+\text{$\omega _{1}$}\frac{z}{\sqrt{z^{2}+1}}$, where…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-01 M. Koussour , N. Myrzakulov , Alnadhief H. A. Alfedeel , E. I. Hassan , D. Sofuoğlu , Safa M. Mirgani

To recreate the cosmological models, we employed the parametrization approach in modified teleparallel Gauss-Bonnet gravity. It has been interesting to apply the parametrization approach to investigate cosmological models. The real benefit…

General Relativity and Quantum Cosmology · Physics 2022-12-29 Santosh V. Lohakare , B. Mishra , S. K. Maurya , Ksh. Newton Singh