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The description of dark matter as a pressure-less fluid and of dark energy as a cosmological constant, both minimally coupled to gravity, constitutes the basis of the concordance $\Lambda\text{CDM}$ model. However, the concordance model is…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-27 Amin Aboubrahim , Pran Nath

We show the effectiveness of using the procedure of the potential reconstruction (the V-method) in the estimation of the transition redshift corresponding to switch from deceleration to acceleration phase of the Universe. We investigate the…

Astrophysics · Physics 2007-05-23 Wojciech Czaja , Marek Szydlowski , Adam Krawiec

We explore locally rotationally symmetric Bianchi I universe in Brans-Dicke gravity with self-interacting potential by using charged viscous cosmological string fluid. We use a relationship between the shear and expansion scalars and also…

General Relativity and Quantum Cosmology · Physics 2015-06-05 M. Sharif , Saira Waheed

In this paper, we search the existence of Bianchi-V string cosmological model in $f(R,T)$ gravity with power law expansion. Einstein's field equations have been solved by taking into account the law of variation of Hubble's parameter that…

General Physics · Physics 2014-09-12 Anil Kumar Yadav

Recently H(z) data obtained from differential ages of galaxies have been proposed as a new geometrical probe of dark energy. In this paper we use those data, combined with other background tests (CMB shift and SNIa data), to constrain a set…

Astrophysics · Physics 2009-11-13 Ruth Lazkoz , Elisabetta Majerotto

Locally rotationally symmetric (L.R.S.) Bianchi type II stiff fluid cosmological model is investigated. To get the deterministic model of the universe, we have assumed a condition $A=B^{m}$ between metric potentials $A,~B$ where $n$ is the…

General Relativity and Quantum Cosmology · Physics 2011-05-26 Hassan Amirhashchi

We investigate a new class of LRS Bianchi type-II cosmological models by revisiting in the paper of Mishra {\it et al} (2013) by considering a new deceleration parameter (DP) depending on the time in string cosmology for the modified…

General Physics · Physics 2021-08-02 Archana Dixit , Rashid Zia , Anirudh Pradhan

We place observational constraints on models with the late-time cosmic acceleration based on a number of parametrizations allowing fast transitions for the equation of state of dark energy. In addition to the model of Linder and Huterer…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Antonio De Felice , Savvas Nesseris , Shinji Tsujikawa

Einstein's field equations with variable gravitational and cosmological ``constant'' are considered in presence of perfect fluid for Bianchi type-I spacetime. Consequences of the four cases of the phenomenological decay of $\Lambda$ have…

General Relativity and Quantum Cosmology · Physics 2008-11-26 J. P. Singh , A. Pradhan , A. K. Singh

We use observational data from Type Ia Supernovae (SN), Baryon Acoustic Oscillations (BAO), Cosmic Microwave Background (CMB) and observational Hubble data (OHD), and the Markov Chain Monte Carlo (MCMC) method, to constrain the cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-13 Jianbo Lu , Emmanuel N. Saridakis , M. R. Setare , Lixin Xu

We consider a model of non-canonical scalar-tensor theory in which the kinetic term in the Brans-Dicke action is replaced by a non-canonical scalar field Lagrangian $\mathcal{L}(X, \phi)= \lambda X^\alpha \phi^\beta - V(\phi)$ where $X =…

General Relativity and Quantum Cosmology · Physics 2025-10-24 Nihal Jalal Pullisseri , Sanil Unnikrishnan

Cosmological models with variable and modified equations of state for dark energy are confronted with observational data, including Type Ia supernovae, Hubble parameter data $H(z)$ from different sources, and observational manifestations of…

General Relativity and Quantum Cosmology · Physics 2022-03-29 German S. Sharov , Vasily E. Myachin

In this paper, the holographic dark energy in Brans-Dicke theory is confronted by cosmic observations from SN Ia, BAO and CMB shift parameter. The best fit parameters are found in $1\sigma$ region: $\Omega_{h0}=0.683^{+0.035}_{-0.038}$,…

Cosmology and Nongalactic Astrophysics · Physics 2009-05-27 Lixin Xu , Jianbo Lu , Wenbo Li

By assuming a phenomenological form for the ratio of the DE and DM densities $\rho_X\propto \rho_{m} a^{\xi}$ (Dalal et al.2001), we discuss the cosmic coincidence problem in light of current observational data. $\xi$ is a key parameter to…

Cosmology and Nongalactic Astrophysics · Physics 2010-03-11 Yun Chen , Zong-Hong Zhu , J. S. Alcaniz , Yungui Gong

Bianchi type V bulk viscous fluid cosmological models are investigated. Using a generation technique (Camci {\it et al.}, 2001), it is shown that the Einstein's field equations are solvable for any arbitrary cosmic scale function. The…

General Relativity and Quantum Cosmology · Physics 2009-07-23 Anirudh Pradhan , Vandana Rai , R. S. Singh

In this paper, we investigate Bianchi type-$VI$ cosmological model for the universe filled with dark energy and viscous fluid in the presence of cosmological constant. Also, we show accelerating expansion of the universe by drawing volume…

General Relativity and Quantum Cosmology · Physics 2013-08-29 J. Sadeghi , Ali R. Amani , N. Tahmasbi

The interacting dark matter (IDM) scenario allows for the acceleration of the Universe without Dark Energy. We constrain the IDM model by using the newly revised observational data including $H(z)$ data and Union2 SNe Ia via the Markov…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Shuo Cao , Zong-Hong Zhu , Nan Liang

In this letter we investigate some consequences of considering our 4D observable universe as locally and isometrically embeded into a 5D spacetime, where gravity is described by a Brans-Dicke theory in vacuum. Once we impose the embeding…

General Relativity and Quantum Cosmology · Physics 2017-06-28 José Edgar Madriz Aguilar , J. Zamarripa , A. Peraza , J. A. Licea

We investigate the viability of the braneworld model with energy exchange between the brane and bulk, by using the most recent observational data related to the background evolution. We show that this energy exchange behaves like a source…

Astrophysics · Physics 2008-07-24 M. Sadegh Movahed , Ahmad Sheykhi

We investigate a class of scalar field dark energy models non-minimally coupled to gravity, characterized by a double exponential potential and parameterized coupling $\xi$. We study the cosmological dynamics for a recently proposed…

General Relativity and Quantum Cosmology · Physics 2025-10-28 Yerlan Myrzakulov , Saddam Hussain , Mohd Shahalam
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