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Anisotropic dark energy model with dynamic pressure anisotropies along different spatial directions is constructed at the backdrop of a spatially homogeneous diagonal Bianchi type $V$ $(BV)$ space-time in the framework of General…

General Physics · Physics 2017-05-10 B. Mishra , S. K. Tripathy

A mildly inhomogeneous universe with a cosmological constant may look like it contains evolving dark energy. We show that could be the case by modelling the inhomogeneities and their effects in three different ways: as clumped matter…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-29 Yonadav Barry Ginat , Pedro G. Ferreira

We implement Crossing Statistics to reconstruct in a model-agnostic manner the expansion history of the universe and properties of dark energy, using DESI Data Release 1 (DR1) BAO data in combination with one of three different supernova…

In order to depict the transition from deceleration to acceleration expansion of the universe we use a power-law expansion scale factor, $a\sim t^{n_0+bt^m}$, with $n_0$, $b$ and $m$ three parameters determined by $H_0$, $q_0$ and $z_T$.…

Astrophysics · Physics 2007-05-23 Yi-Huan Wei

Recent findings from the Dark Energy Spectroscopic Instrument (DESI), analyzed together with supernova observations and CMB measurements, provide statistically significant indications (at the 2-5$\sigma$ level) of a time-varying dark energy…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-12 Nandan Roy , Soumya Chakrabarti

Over the last few years a certain class of dark-energy models decaying inversely proportional to the square of the horizon distance emerged on the basis either of Heisenberg uncertainty relations or of the uncertainty relation between the…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-12 Michael Maziashvili

It has, quite recently, become fashionable to study a certain class of holographic-inspired models for the dark energy. These investigations have, indeed, managed to make some significant advances towards explaining the empirical data.…

High Energy Physics - Theory · Physics 2009-02-18 A. J. M. Medved

We consider a holographic dark energy model, in which both the CC energy density rho_Lambda and the Newton constant G_N are varying quantities, to study the problem of setting an effective field-theory IR cutoff. Assuming that ordinary…

Astrophysics · Physics 2008-11-26 B. Guberina , R. Horvat , H. Nikolic

We generalize tensor-scalar theories of gravitation by the introduction of an abnormally weighting type of energy. This theory of tensor-scalar anomalous gravity is based on a relaxation of the weak equivalence principle that is now…

Astrophysics · Physics 2009-01-14 J. -M. Alimi , A. Füzfa

In this work we have investigated the inflation mechanism driven by the Barrow Holographic dark energy (BHDE) in the early universe. BHDE is based on the Barrow relation for horizon entropy, which in turn is inspired from the shape of the…

General Relativity and Quantum Cosmology · Physics 2022-02-17 Sayani Maity , Prabir Rudra

The interacting and holographic dark energy models involve two important quantities. One is the characteristic size of the holographic bound and the other is the coupling term of the interaction between dark energy and dark matter. Rather…

High Energy Physics - Theory · Physics 2008-11-26 Bo Hu , Yi Ling

One of the main aims in the next generation of precision cosmology experiments will be an accurate determination of the equation of state (EOS) for the dark energy (DE). If the latter is dynamical, the resulting barotropic index \omega…

Astrophysics · Physics 2009-11-13 Joan Sola , Hrvoje Stefancic

We reconsider the holographic dark energy (HDE) model with a slowly time varying $ c^2(z)$ parameter in the energy density, namely $\rho_D=3M_p^2 c^2(z)/L^2$, where $L$ is the IR cutoff and $z$ is the redshift parameter. As the system's IR…

General Physics · Physics 2017-06-06 A. Sheykhi , S. Ghaffari , N. Roshanshah

The current vacuum energy density observed as dark energy ${ \rho }_{ \rm dark }\simeq 2.5\times10^{-47}\ {\rm GeV^{4}}$ is unacceptably small compared with any other scales. Therefore, we encounter serious fine-tuning problem and…

High Energy Physics - Theory · Physics 2017-06-07 Kazunori Kohri , Hiroki Matsui

We present a model of holographic dark energy in which the Infrared cutoff is determined by both the Ricci and the Gauss-Bonnet invariants. Such a construction has the significant advantage that the Infrared cutoff, and consequently the…

General Relativity and Quantum Cosmology · Physics 2018-04-06 Emmanuel N. Saridakis

The presence of dark energy at high redshift influences both the cosmic sound horizon and the distance to last scattering of the cosmic microwave background. We demonstrate that through the degeneracy in their ratio, early dark energy can…

Astrophysics · Physics 2009-06-23 Eric V. Linder , Georg Robbers

We suggest that vacuum entanglement energy associated with the entanglement entropy of the universe is the origin of dark energy. The observed properties of dark energy can be explained by using the nature of entanglement energy without…

High Energy Physics - Theory · Physics 2010-10-27 Jae-Weon Lee , Jungjai Lee , Hyeong-Chan Kim

Time variable cosmological constant (TVCC) of holographic origin with interaction in Brans-Dicke theory is discussed in this paper. We investigate some characters for this model, and show the evolutions of deceleration parameter and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Jianbo Lu , Lina Ma , Molin Liu , Yabo Wu

In this work, a way to consider together two originally different corrections to the Friedmann equations is presented. The first is the Barrow entropy, which imposes a fractal structure on the black hole horizon area. While the second is…

General Relativity and Quantum Cosmology · Physics 2022-11-23 P. S. Ens , A. F. Santos

Cosmic acceleration is explained quantitatively, purely in general relativity, as an apparent effect due to quasilocal gravitational energy differences that arise in the decoupling of bound systems from the global expansion of the universe.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 David L. Wiltshire