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In this paper, we have examined the recently proposed modified symmetric teleparallel gravity, in which gravitational Lagrangian is given by an arbitrary function of non-metricity scalar $Q$. We have considered a constant jerk parameter to…

General Relativity and Quantum Cosmology · Physics 2023-02-28 M. Koussour , S. Dahmani , M. Bennai , T. Ouali

We discuss influences of bulk viscosity on the Early Universe, which is modeled by Friedmann-Robertson-Walker metric and Einstein field equations. We assume that the matter filling the isotropic and homogeneous background is relativistic…

General Relativity and Quantum Cosmology · Physics 2009-12-02 A. Tawfik , H. Mansour , M. Wahba

We consider the influence of the perturbative bulk viscosity on the evolution of the Hubble parameter in the QCD era of the early Universe. For the geometry of the Universe we assume the homogeneous and isotropic…

General Relativity and Quantum Cosmology · Physics 2010-11-24 A. Tawfik , M. Wahba , H. Mansour , T. Harko

Since the late 1990's observations of type Ia Supernova, our universe is predicted to experience a late time cosmic acceleration. Theoretical support to this observation were intended to be built via proposition of a hypothetical fluid…

General Relativity and Quantum Cosmology · Physics 2020-08-10 Promila Biswas , Parthajit Roy , Ritabrata Biswas

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

This research investigates the impact of modified gravity on cosmic scales, focusing on $f(Q)$ cosmology. By applying energy conditions, the study reconstructs various $f(Q)$ models, considering an accelerating Universe, quintessence, and a…

General Relativity and Quantum Cosmology · Physics 2025-04-14 Irfan Mahmood , Hira Sohail , Allah Ditta , S. H. Shekh , Anil Kumar Yadav

In this paper, we focus on the parametrization of the effective equation of state (EoS) parameter within the framework of $f(Q)$ symmetric teleparallel gravity. Here, the gravitational action is represented by an arbitrary function of the…

General Relativity and Quantum Cosmology · Physics 2023-07-04 A. Mussatayeva , N. Myrzakulov , M. Koussour

In a spatially flat universe and for an interacting cosmology, we have reconstructed the interaction term, $Q$, between a cold dark matter (DM) fluid and a dark energy (DE) fluid, as well as a time-varying equation of state (EoS) parameter…

General Relativity and Quantum Cosmology · Physics 2018-09-27 Freddy Cueva Solano

This article motivated by the recent articles and results of two authors. Recently, J. Sadeghi and H. Farahani presented a work [1], where they include viscosity and analyze general model, by this way they extended models considered by M.…

General Relativity and Quantum Cosmology · Physics 2016-01-05 J. Sadeghi , M. Khurshudyan , H. Farahani

A generally parameterized equation of state (EOS) is investigated in the cosmological evolution with bulk viscosity media modelled as dark fluid, which can be regarded as a unification of dark energy and dark matter. Compared with the case…

Astrophysics · Physics 2009-11-13 J. Ren , Xin He Meng

Models with non-gravitational interactions between the dark matter and dark energy components are an alternative to the standard cosmological scenario. These models are characterized by an interaction term, and a frequently used…

General Relativity and Quantum Cosmology · Physics 2020-12-07 R. von Marttens , H. A. Borges , S. Carneiro , J. S. Alcaniz , W. Zimdahl

We consider a fluid described by a parameterized EoS of the general form $P=(\gamma-1)\rho+p_{0}+\omega_{H}H+\omega_{H2}H^{2}+\omega_{dH}\dot{H}$ \cite{Ren}, where $p_{0}$, $\omega_{H}$, $\omega_{H2}$ and $\omega_{dH}$ are free parameters…

General Physics · Physics 2013-08-06 Martiros Khurshudyan

We present a new $f(Q)$ cosmological model capable of reproducing late-time acceleration, i.e. $f\left( Q\right) = \lambda_{0}\left( \lambda +Q\right) ^{n}$ by supporting certain parametrization of the Hubble parameter. By using…

General Relativity and Quantum Cosmology · Physics 2023-06-26 N. Myrzakulov , M. Koussour , Dhruba Jyoti Gogoi

We revise the conditions for the physical viability of a cosmological model in which dark matter has bulk viscosity and also interacts with dark energy. We have also included radiation and baryonic matter components; all matter components…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Arturo Avelino , Yoelsy Leyva , L. Arturo Urena-Lopez

In the present chapter, we have established multiple fluid cosmological models under interaction scenarios. the interaction model we have established is a binary type of interaction scenario where three types of fluids are bound with…

General Relativity and Quantum Cosmology · Physics 2023-04-14 Alokananda Kar , Shouvik Sadhukhan

Interactions between cosmic fluids may appear in many cosmological scenarios that go far beyond the usually studied energy exchange in the dark sector. In the absence of known microscopic interaction mechanisms, phenomenological ansatzes…

General Relativity and Quantum Cosmology · Physics 2015-07-28 M. R. G. Maia , N. Pires , H. S. Gimenes

Gravitational and hydrodynamical perturbations are analysed in a relativistic plasma containing a mixture of interacting fluids characterized by a non-negligible bulk viscosity coefficient. The energy-momentum transfer between the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Massimo Giovannini

In this work, we study a Dark Energy (DE) energy density model which depends on the Hubble parameter squared $H^2$ and on its first, second and third time derivatives $\dot{H}$, $\ddot{H}$ and $\dddot{H}$. Considering a scale factor $a$…

General Relativity and Quantum Cosmology · Physics 2025-10-23 Antonio Pasqua

In this paper we study the interaction between the general form of viscous varying modified cosmic Chaplygin gas and the Tachyon fluid in the framework of Einstein gravity. We want to reconstruct the Tachyon potential and total equation of…

General Relativity and Quantum Cosmology · Physics 2013-08-05 Jafar Sadeghi , Hoda Farahani

The purpose of this short review is to describe cosmological models with a linear inhomogeneous time-dependent equation of state (EoS) for the dark energy, when the dark fluid is coupled with dark matter. This may lead to a bounce…

General Relativity and Quantum Cosmology · Physics 2015-03-17 Iver Brevik , Alexander Timoshkin