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We use three IR cutoffs, including the future event horizon, the Hubble and Granda-Oliveros (GO) cutoffs, to construct three holographic models of dark energy. Additionally, we consider a Friedmann-Robertson-Walker (FRW) universe filled by…

General Relativity and Quantum Cosmology · Physics 2017-06-06 M. Abdollahi Zadeh , A. Sheykhi , H. Moradpour

We consider a specific dark energy model, which only includes the Lagrangian up to the cubic order in terms of the vector field self-interactions in the generalized Proca theory. We examine the cosmological parameters in the model by using…

General Relativity and Quantum Cosmology · Physics 2021-04-22 Chao-Qiang Geng , Yan-Ting Hsu , Jhih-Rong Lu , Lu Yin

In this study, cosmological models are considered, where dark matter and dark energy are coupled and may exchange energy through non-gravitational interactions with one other. These interacting dark energy (IDE) models have previously been…

General Relativity and Quantum Cosmology · Physics 2024-01-23 Marcel A. van der Westhuizen , Amare Abebe

A novel fractal structure for the cosmological horizon, inspired by COVID-19 geometry, which results in a modified area entropy, is applied to cosmology in order to serve dark energy. The constraints based on a complete set of observational…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-18 Mariusz P. Dabrowski , Vincenzo Salzano

We test the $n$=3 Ultralight Axion-like model of Early Dark Energy (EDE) with the observationsof the $EB$ mode of the cosmic microwave background (CMB) radiation, and local expansion rate measurements. Our results show that the shape of the…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-14 Joby Kochappan , Lu Yin , Bum-Hoon Lee , Tuhin Ghosh

Addressing the discrepancy between the late and early time measurements of the Hubble parameter, $H_0$, and the so-called $S_8$ parameter has been a challenge in precision cosmology. Several models are present to address these tensions, but…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-02 Ido Ben-Dayan , Utkarsh Kumar

We investigate a generalized form of the phenomenologically emergent dark energy model, known as generalized emergent dark energy (GEDE), introduced by Li and Shafieloo [Astrophys. J. {\bf 902}, 58 (2020)] in light of a series of…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-15 Weiqiang Yang , Eleonora Di Valentino , Supriya Pan , Arman Shafieloo , Xiaolei Li

We introduce a unified model of early and late dark energy. We call it {\it quintessential early dark energy} model where early and late dark energy are explained by a single scalar field {\it i.e.}, two different energy scales are related…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-19 Sk. Sohail , Sonej Alam , Shiriny Akthar , Md. Wali Hossain

In the present article, we propose a very simple parametrization of the Hubble function without parametrizing the dark components of the Universe. One of the novelties of the parametrization is that it may include a wide variety of the…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-12 Sivasish Paul , Raj Kumar Das , Supriya Pan

The Bekenstein-Hawking entropy is a cornerstone of horizon thermodynamics but quantum effects correct it, while inequivalent entropies arise also in non-extensive thermodynamics. Reviewing our previous work, we advocate for a new entropy…

General Relativity and Quantum Cosmology · Physics 2023-01-25 Shin'ichi Nojiri , Sergei D. Odintsov , Valerio Faraoni

Dark energy is modelled by a Bose-Einstein gas of particles with an attractive interaction. It is coupled to cold dark matter, within a flat universe, for the late-expansion description, producing variations in particle-number densities.…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-11 Hiram E. Lucatero--Villaseñor , German Izquierdo , Jaime Besprosvany

We explore the properties of dark energy from recent observational data, including the Gold Sne Ia, the baryonic acoustic oscillation peak from SDSS, the CMB shift parameter from WMAP3, the X-ray gas mass fraction in cluster and the Hubble…

Astrophysics · Physics 2008-11-26 Puxun Wu , Hongwei Yu

Holographic dark energy (HDE) describes the vacuum energy in a cosmic IR region whose total energy saturates the limit of avoiding the collapse into a black hole. HDE predicts that the dark energy equation of the state transiting from…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-04 Wei-Ming Dai , Yin-Zhe Ma , Hong-Jian He

Minimal dark energy models, described by the same number of free parameters of the standard cosmological model with cold dark matter plus a cosmological constant to parameterize the dark energy component, constitute very appealing scenarios…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-25 Eleonora Di Valentino , Stefano Gariazzo , Carlo Giunti , Olga Mena , Supriya Pan , Weiqiang Yang

Axion-like early dark energy (EDE) as an extension to $\Lambda$CDM has been proposed as a possible solution to the 'Hubble tension'. We revisit this model using a new cosmic microwave background (CMB) temperature and polarization likelihood…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-02 George Efstathiou , Erik Rosenberg , Vivian Poulin

We construct Barrow holographic dark energy in the case of non-flat universe. In particular, considering closed and open spatial geometry we extract the differential equations that determine the evolution of the dark-energy density…

General Relativity and Quantum Cosmology · Physics 2021-11-01 Priyanka Adhikary , Sudipta Das , Spyros Basilakos , Emmanuel N. Saridakis

A new dark energy model called "ghost dark energy" was recently suggested to explain the observed accelerating expansion of the universe. This model originates from the Veneziano ghost of QCD. The dark energy density is proportional to…

High Energy Physics - Theory · Physics 2015-03-19 A. Sheykhi , M. Sadegh Movahed

We consider a 12-parameter cosmological model with non-phantom dynamical dark energy (NPDDE), where non-phantom implies that the equation of state (EoS) of dark energy (DE), $w(z)\geq-1$ for all redshifts $z$. Thus, the DE EoS covers the…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-20 Shouvik Roy Choudhury , Teppei Okumura , Keiichi Umetsu

The energy density of the holographic dark energy is based on the area law of entropy, and thus any modification of the area law leads to a modified holographic energy density. Inspired by the entropy expression associated with the apparent…

General Relativity and Quantum Cosmology · Physics 2016-03-16 A. Sheykhi , M. H. Dehghani , S. Ghaffari

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…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-16 Udit K. Tyagi , Sandeep Haridasu , Soumen Basak