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For the first time, we reconstruct the dark energy equation of the state parameter $w$ from the combination of background and perturbation observations, specifically combining the Hubble parameter data from cosmic chronometer observations…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-15 Bikash R. Dinda , Narayan Banerjee

We consider a model-independent approach to constrain the equivalence redshift, $z_{eq}$, at which dark energy and the total matter (cold dark matter and baryonic) equate their magnitudes. To this aim, in the context of a homogeneous and…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-31 Anna Chiara Alfano , Carlo Cafaro , Salvatore Capozziello , Orlando Luongo

The nature of dark energy is one of the fundamental problems in cosmology. Introduced to explain the apparent acceleration of the Universe's expansion, its origin remains to be determined. In this paper, we illustrate a result that may…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-10 Mauro Carfora , Francesca Familiari

This study investigates the cosmological implications of $f(R,\Sigma,T)$ gravity by reconstructing the Hubble parameter from a logarithmic parameterization of the $O_m(z)$ diagnostic. Our approach offers a model-independent way to probe the…

General Relativity and Quantum Cosmology · Physics 2026-05-12 N. Myrzakulov , Anirudh Pradhan , Anil Kumar Yadav , S. H. Shekh

Two very different methods are used to estimate the magnitude of the effective cosmological constant / dark energy (for the present cosmic epoch). Their results agree with each other and are in agreement with observations. One method makes…

General Relativity and Quantum Cosmology · Physics 2017-06-15 Y. Jack Ng

Observational evidence for the existence of dark energy is strong. Here we suggest a model which is based on a modified gravitational theory in 5D and interpret the 5th dimension as a manifestation of dark energy in the 4D observable…

High Energy Physics - Theory · Physics 2008-01-22 H. Alavirad , N. Riazi

We propose a cosmological model that makes a significant step toward solving the coincidence problem of the near similarity at the present of the dark energy and dark matter components. Our cosmology has the following properties: a) among…

Astrophysics · Physics 2008-11-26 Luca Amendola , Domenico Tocchini-Valentini

We study a cosmological model in which phantom dark energy is coupled to dark matter by phenomenologically introducing a coupled term to the equations of motion of dark energy and dark matter. This term is parameterized by a dimensionless…

High Energy Physics - Theory · Physics 2009-11-10 Rong-Gen Cai , Anzhong Wang

Dark energy appears to be the dominant component of the physical Universe, yet there is no persuasive theoretical explanation for its existence or magnitude. The acceleration of the Universe is, along with dark matter, the observed…

This is an essay sketching the line of thinking which has led the present author to propose the constituent or atomic model of gravitation more than a decade ago. It turns out that viewing the problem of gravitation as a quantum many body…

Astrophysics · Physics 2009-10-19 Pawel O. Mazur

In this paper, we investigate static spherically symmetric solutions in the context of Conformal Killing Gravity, a recently proposed modified theory of gravity that offers a new approach to the cosmological constant problem. Coupling this…

The paper deals with a spatially homogeneous and isotropic FRW space-time filled with perfect fluid and dark energy components. The two sources are assumed to interact minimally, and therefore their energy momentum tensors are conserved…

General Relativity and Quantum Cosmology · Physics 2014-08-21 Suresh Kumar

We investigate the global dynamics of the universe within the framework of the Interacting Dark Matter (IDM) scenario. Considering that the dark matter obeys the collisional Boltzmann equation, we can obtain analytical solutions of the…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Spyros Basilakos , Manolis Plionis

Cosmology enters precision testing period with the observational experiments advancement. We have not arrived to decipher the origin of the dominant dark energy component of our universe, although we have located some of its characters. In…

High Energy Physics - Phenomenology · Physics 2007-05-23 Tomohiro Inagaki , Xinhe Meng , Tsukasa Murata

We use the effective field theory of dark energy to explore the space of modified gravity models which are capable of driving the present cosmic acceleration. We identify five universal functions of cosmic time that are enough to describe a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Federico Piazza , Heinrich Steigerwald , Christian Marinoni

We provide preliminary quantitative evidence that a new solution to averaging the observed inhomogeneous structure of matter in the universe [gr-qc/0702082, arxiv:0709.0732], may lead to an observationally viable cosmology without exotic…

Astrophysics · Physics 2008-11-26 Ben M. Leith , S. C. Cindy Ng , David L. Wiltshire

The cosmological implications of the Covariant Canonical Gauge Theory of Gravity (CCGG) are investigated. We deduce that, in a metric compatible geometry, the requirement of covariant conservation of matter invokes torsion of space-time. In…

General Relativity and Quantum Cosmology · Physics 2024-10-28 David Vasak , Johannes Kirsch , Juergen Struckmeier

A successor to the standard hot big-bang cosmology is emerging. It greatly extends the highly successful hot big-bang model. A key element of the New Standard Cosmology is dark energy, the causative agent for accelerated expansion. Dark…

Astrophysics · Physics 2007-05-23 Michael S. Turner

The observed dark energy in the universe might give particles inertial mass. We investigate one realization of this idea, that the dark energy field might be a decayed scalar component of a supermultiplet field in the early universe that…

Astrophysics · Physics 2007-05-23 Robert J. Nemiroff , Bijunath Patla

We consider a set of solutions for a massless quartic scalar field, recently devised, that satisfy a massive dispersion relation. We show that such solutions have the property to give the correct behavior for the equation of state of the…

High Energy Physics - Phenomenology · Physics 2020-04-27 Marco Frasca
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