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Several independent cosmological data, collected within the last twenty years, revealed the accelerated expansion rate of the Universe, usually assumed to be driven by the so called dark energy, which, according to recent estimates,…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-16 Marek Demianski , Elisabeta Lusso , Maurizio Paolillo , Ester Piedipalumbo , Guido Risaliti

In this work we examine the possibility that the dark energy (DE) density, $\rho_{de}$ can be dynamical and appear as a power series expansion of the Hubble rate (and its derivatives), i.e.$\rho_{de}(H,\dot{H},...)$. For the present…

General Relativity and Quantum Cosmology · Physics 2019-07-30 Mehdi Rezaei , Mohammad Malekjani , Joan Sola

Measurements of the current expansion rate of the Universe, $H_0$, using standard candles, disagree with those derived from observations of the Cosmic Microwave Background (CMB). This discrepancy, known as the Hubble tension, is substantial…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-05 Sergio Torres-Arzayus

Dynamical dark energy has been recently suggested as a promising and physical way to solve the 3.4 sigma tension on the value of the Hubble constant $H_0$ between the direct measurement of Riess et al. (2016) (R16, hereafter) and the…

Cosmology and Nongalactic Astrophysics · Physics 2017-07-24 Eleonora Di Valentino , Alessandro Melchiorri , Eric V. Linder , Joseph Silk

In this paper bulk viscosity is introduced to describe the effects of cosmic non-perfect fluid on the cosmos evolution and to build the unified dark energy (DE) with (dark) matter models. Also we derive a general relation between the bulk…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-14 X. H. Meng , X. Dou

So far large and different data sets revealed the accelerated expansion rate of the Universe, which is usually explained in terms of dark energy. The nature of dark energy is not yet known, and several models have been introduced: a non…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-16 M. Demianski , E. Piedipalumbo , D. Sawant , L. Amati

The Dark Energy Spectroscopic Instrument (DESI) collaboration recently released the first year data of baryon acoustic oscillations (BAOs). Based on the five different tracers, the cosmological constraint shows a hint of deviation from the…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-16 X. D. Jia , J. P. Hu , S. X. Yi , F. Y. Wang

With data from Pantheon, we have at our disposal a sample of more than a thousand supernovae Ia covering a wide range of redshifts with good precision. Here we make fits to the corresponding Hubble--Lema\^itre diagram with various…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-07 M. Lopez-Corredoira , J. I. Calvo-Torel

I review the excellent phenomenological status of a class of dynamical vacuum models in which the vacuum energy density, $\rho_{\Lambda}=\rho_{\Lambda}(H)$, as a function of the Hubble rate, evolves through its interaction with dark matter…

General Relativity and Quantum Cosmology · Physics 2016-01-15 Joan Sola

We propose a revised formulation of General Relativity for cosmological settings, in which the Einstein constant varies with the energy density of the Universe. We demonstrate that this modification has only phenomenological impact of…

General Relativity and Quantum Cosmology · Physics 2025-08-28 Giovanni Montani , Giulia Maniccia , Elisa Fazzari , Alessandro Melchiorri

Three general cases of dynamical interacting dark energy models ($\mathcal{D}$-class) are investigated in the context of Brans-Dicke cosmology. Some of important cosmological quantities are calculated for every cases as a function of…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-28 E. Karimkhani , A. Khodam-Mohammadi

We compute the Bayesian evidences for one- and two-parameter models of evolving dark energy, and compare them to the evidence for a cosmological constant, using current data from Type Ia supernova, baryon acoustic oscillations, and the…

Astrophysics · Physics 2008-11-26 Andrew R Liddle , Pia Mukherjee , David Parkinson , Yun Wang

The current paper provides a comprehensive examination of a dark energy cosmological model in the classical regime, in which a generic scalar field is regarded as a dark energy source. Einstein's field equations are solved in model…

General Relativity and Quantum Cosmology · Physics 2022-09-07 Ritika Nagpal , Shibesh Kumar Jas Pacif , Abhishek Parida

The latest improvements in the scale and calibration of Type Ia supernovae catalogues allow us to constrain the specific nature and evolution of dark energy through its effect on the expansion history of the universe. We present the results…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-05 Toby Lovick , Suhail Dhawan , Will Handley

In this paper, bulk viscosity is introduced in new holographic dark energy (HDE) to describe the effects of cosmic non-perfect fluid on the evolution of the universe in modified $f(R,T)$ gravity. Assuming $f(R,T)=R+\lambda T$, where $R$ is…

General Relativity and Quantum Cosmology · Physics 2018-04-17 C P Singh , Milan Srivastava

We constrain two non-flat time-evolving dark energy cosmological models by using Hubble parameter data, Type Ia supernova apparent magnitude measurements, and baryonic acoustic oscillation peak length scale observations. The inclusion of…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-22 Omer Farooq , Data Mania , Bharat Ratra

We present logistic dark energy model (LDEM), where the dark energy density follows a logistic function for the scale factor. The equation of state parameter of dark energy ($w_D$) transitioned from $-1$ in the distant past to its current…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-27 Sarath Nelleri , Gopi Krishna , Navaneeth Poonthottathil

In the $\Lambda$CDM model, dark energy is viewed as a constant vacuum energy density, the cosmological constant in the Einstein--Hilbert action. This assumption can be relaxed in various models that introduce a dynamical dark energy. In…

High Energy Physics - Theory · Physics 2020-11-19 Vishnu Jejjala , Michael J. Kavic , Djordje Minic , Tatsu Takeuchi

We propose a dark energy model based on the physics of critical phenomena which is consistent with both the Planck's CMB and the Riess et al.'s local Hubble measurements. In this model the dark energy density behaves like the magnetization…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-09 Abdolali Banihashemi , Nima Khosravi , Arman Shafieloo

Here we test different models of dark energy beyond the standard cosmological constant scenario. We start considering the CPL parameterization of the equation of state (EOS), then we consider a dark energy scalar field (Quintessense).…

High Energy Astrophysical Phenomena · Physics 2018-02-07 Marek Demianski , Ester Piedipalumbo , Disha Sawant , Lorenzo Amati