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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 David H. Weinberg , Michael J. Mortonson , Daniel J. Eisenstein , Christopher Hirata , Adam G. Riess , Eduardo Rozo

There are many kinds of models which describe the dynamics of dark energy (DE). Among all we adopt an equation of state (EoS) which varies as a function of time. We adopt Markov Chain Monte Carlo method to constrain the five parameters of…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-15 R. Ichimasa , E. P. B. A. Thushari , M. Hashimoto

In this paper, we propose a new pressure parametric model of the total cosmos energy components in a spatially flat Friedmann-Robertson-Walker (FRW) universe and then reconstruct the model into quintessence and phantom scenarios,…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-14 Jun-Chao Wang , Xin-He Meng

We show that the latest empirical constraints on cosmology, from a combination of DESI, CMB and supernova data, can be accounted for if a small component of dark matter has an evolving and oscillating equation of state within $-1<w<1$. From…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-22 Xingang Chen , Abraham Loeb

The Dark Energy Spectroscopic Instrument (DESI) collaboration has recently released measurements of baryon acoustic oscillation (BAO) from the first year of observations. A joint analysis of DESI BAO, CMB, and SN Ia probes indicates a…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-02 Anton Chudaykin , Martin Kunz

The dynamical aspect of accelerating cosmological model has been studied in this paper in the context of modified symmetric teleparallel gravity, the $f(Q)$ gravity. Initially, we have derived the dynamical parameters for two well known…

General Relativity and Quantum Cosmology · Physics 2023-07-18 S. A. Narawade , Shashank P. Singh , B. Mishra

We use a parameterized equation of state (EOS) of dark energy to a 5D Ricci-flat cosmological solution and suppose the universe contains two major components: dark matter and dark energy. Using the recent observational datasets: the latest…

Astrophysics · Physics 2009-06-23 Chengwu Zhang , Lixin Xu , Yongli Ping , Hongya Liu

In this study, we use a flexible parametrization of the equation of state of dark energy to explore its possible evolution with datasets from the Dark Energy Spectroscopic Instrument (DESI), Planck cosmic microwave background, and either…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-14 Ryan E. Keeley , Kevork N. Abazajian , Manoj Kaplinghat , Arman Shafieloo

This article discusses a dark energy cosmological model in the standard theory of gravity - general relativity with a broad scalar field as a source. Exact solutions of Einstein's field equations are derived by considering a particular form…

General Relativity and Quantum Cosmology · Physics 2022-08-23 S. K. J. Pacif , Simran Arora , P. K. Sahoo

We constrain the parameters of dynamical dark energy in the form of a classical or tachyonic scalar field with barotropic equation of state jointly with other cosmological ones using the combined datasets which include the CMB power spectra…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Olga Sergijenko , Ruth Durrer , Bohdan Novosyadlyj

This review summarizes recent attempts to reconstruct the expansion history of the Universe and to probe the nature of dark energy. Reconstruction methods can be broadly classified into parametric and non-parametric approaches. It is…

Astrophysics · Physics 2008-11-26 Varun Sahni , Alexei Starobinsky

We use the Busca et al. (2012) measurement of the Hubble parameter at redshift z = 2.3 in conjunction with 21 lower z measurements, from Simon et al. (2005), Gaztanaga et al. (2009), Stern et al. (2010), and Moresco et al. (2012), to place…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Omer Farooq , Bharat Ratra

We adopt a model independent method to reconstruct the dark energy equation of state by analyzing 5 sets of SNe Ia data along with Baryon Acoustic Oscillation (BAO) and Observational Hubble Data (OHD). The SNe Ia data sets include the most…

Cosmology and Nongalactic Astrophysics · Physics 2011-03-15 Debabrata Adak , Abhijit Bandyopadhyay , Debasish Majumdar

We study dynamical dark energy models within Einstein's theory by means of matter perturbations and the growth index $\gamma$. Within four-dimensional General Relativity, we assume that dark energy does not cluster, and we adopt a linear…

General Relativity and Quantum Cosmology · Physics 2023-06-07 G. Panotopoulos , G. Barnert , L. E. Campusano

We study the possibility of detecting oscillating patterns in the equation of state (EoS) of the dark energy using different cosmological datasets. We follow a phenomenological approach and study three different oscillating models for the…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-09 Ruth Lazkoz , Vincenzo Salzano , Irene Sendra

In this work we explore a Holographic Dark Energy Model in a flat Friedmann-Lema\^itre-Robertson-Walker Universe, which contains baryons, radiation, cold dark matter and dark energy within the framework of General Relativity. Furthermore,…

General Relativity and Quantum Cosmology · Physics 2019-05-10 Carlos Rodriguez-Benites , Mauricio Cataldo , Antonella Cid , Carlos Ríos

Dark energy models with a single scalar field cannot cross the equation of state divide set by a cosmological constant. More general models that allow crossing require additional degrees of freedom to ensure gravitational stability. We show…

Astrophysics · Physics 2008-12-01 Wenjuan Fang , Wayne Hu , Antony Lewis

In this paper, we present a comprehensive cosmological analysis within the framework of $f(R, \Sigma, T)$ gravity, a modified theory that incorporates nonlinear matter-geometry coupling via the inclusion of both the trace of the…

General Relativity and Quantum Cosmology · Physics 2025-11-24 S. H. Shekh , N. Myrzakulov , Anil Kumar Yadav , Anirudh Pradhan

In this work, we derive a generalized modified Friedmann equation based on an entropy-area relation that incorporates established modifications, such as volumetric, linear, and logarithmic terms, in addition to novel entropic modifications…

General Relativity and Quantum Cosmology · Physics 2024-12-17 Javier Chagoya , I. Díaz-Saldaña , Mario H. Amante , J. C. López-Domínguez , M. Sabido

Among the various possibilities to probe the theory behind the recent accelerated expansion of the universe, the energy conditions (ECs) are of particular interest, since it is possible to confront and constrain the many models, including…

General Relativity and Quantum Cosmology · Physics 2018-09-17 M. E. S. Alves , F. C. Carvalho , J. C. N. de Araujo , M. Penna-Lima , S. D. P. Vitenti