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In this study, we have explored a transitioning cosmological model of universe's expansion in $f(R,\mathcal{L}_{m})$ gravity. The quadratic type of equation of state parameter in the form $\omega=-1 + \alpha (1 + z) + \beta (1 + z)^2$,…

General Relativity and Quantum Cosmology · Physics 2025-04-16 Vinod Kumar Bhardwaj , Saibal Ray

The South Pole Telescope (SPT), using its third-generation camera, SPT-3G, is conducting observations of the cosmic microwave background (CMB) in temperature and polarization across approximately 10 000 deg$^2$ of the sky at 95, 150, and…

We propose a logarithmic parametrization form of energy density for the scalar field dark energy in the framework of the standard theory of gravity, which supports the necessary transition from the decelerated to the accelerated behavior of…

General Relativity and Quantum Cosmology · Physics 2023-07-31 Dan Wang , M. Koussour , Adnan Malik , N. Myrzakulov , G. Mustafa

A new parametrization of the Hubble parameter is proposed to explore the issue of the cosmological landscape. The constraints on model parameters are derived through the Markov Chain Monte Carlo (MCMC) method by employing a comprehensive…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-06 L. Sudharani , Kazuharu Bamba , N. S. Kavya , V. Venkatesha

We explore the possibility of describing our universe with a singularity--free, closed, spatially homogeneous and isotropic cosmological model, using only general relativity and a suitable equation of state which produces an inflationary…

Astrophysics · Physics 2010-11-01 S. S. Bayin , F. I. Cooperstock , V. Faraoni

The Hubble parameter is one of the central parameters in modern cosmology, which describes the present expansion rate of the universe. Their values inferred from the late-time observations are systematically higher than those from the…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-02 Renjie Wang , Wen-Hong Ruan , Qing Yang , Zong-Kuan Guo , Rong-Gen Cai , Bin Hu

Class of spherically symmetric Stephani cosmological models is examined in the context of evolution type. It is assumed that the equation of state at the symmetry center of the models is barotropic. Classification of cosmological models is…

Astrophysics · Physics 2009-11-13 Izabela Jakacka , Jerzy Stelmach

Accurately measuring the Hubble parameter is vital for understanding the expansion history and properties of the universe. In this paper, we propose a new method that supplements the covariance between redshift pairs to improve the…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-23 Jian-Chen Zhang , Yu Hu , Kang Jiao , Hong-Feng Wang , Yuan-Bo Xie , Bo Yu , Li-Li Zhao , Tong-Jie Zhang

We investigate observational constraints on dark energy models from lookback time (LT) estimates of 32 old passive galaxies distributed over the redshift interval $0.11 \leq z \leq 1.84$. To build up our LT sample we combine the age…

Cosmology and Nongalactic Astrophysics · Physics 2009-09-28 M. A. Dantas , J. S. Alcaniz , N. Pires

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

In this work, the cosmic solutions, particularly the well-known $\Lambda$CDM model, are investigated in the framework of the Gauss-Bonnet gravity, where the gravitational action incorporates the Gauss-Bonnet invariant function. We utilize a…

General Relativity and Quantum Cosmology · Physics 2024-09-26 N. Myrzakulov , Anirudh Pradhan , Archana Dixit , S. H. Shekh

We use cosmography to present constraints on the kinematics of the Universe without postulating any underlying theoretical model a priori. To this end, we use a Markov Chain Monte Carlo analysis to perform comparisons to the supernova Ia…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-18 Alejandro Aviles , Christine Gruber , Orlando Luongo , Hernando Quevedo

In this paper, the dynamical behavior of the accelerated expansion of the universe is discussed within the framework of $f(T)$ gravity, considering power law functional form of $ f(T)=\alpha (-T)^{n}$. Two distinct redshift-dependent…

General Relativity and Quantum Cosmology · Physics 2025-08-29 Shivank Pal , Romanshu Garg , Gyan Prakash Singh , Gauree Shanker

We explore a cosmological model based on R\'enyi entropic corrections to the Friedmann equations and constrain it using DESI, P-BAO, CC, and gravitational-wave observations. Unlike earlier works, we obtain a direct and stringent constraint…

General Relativity and Quantum Cosmology · Physics 2026-04-27 Rajdeep Mazumdar , Kalyan Malakar , Kalyan Bhuyan

We consider a cosmology with decaying metastable dark energy and assume that a decay process of this metastable dark energy is a quantum decay process. Such an assumption implies among others that the evolution of the Universe is…

General Relativity and Quantum Cosmology · Physics 2019-09-27 Aleksander Stachowski , Marek Szydlowski , Krzysztof Urbanowski

We investigate a relativistic cosmological model with background rotation, sourced by a non-perfect fluid with anisotropic stress. A modified version of the CLASS Boltzmann code is employed to perform Monte Carlo Markov Chain analyses…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-16 Micol Benetti , David A. Cook , Saulo Carneiro

We examine the observational viability of a class of $f(\mathcal{R})$ gravity cosmological models. Particular attention is devoted to constraints from the recent observational determination of the redshift of the cosmological…

General Relativity and Quantum Cosmology · Physics 2015-06-19 Salvatore Capozziello , Omer Farooq , Orlando Luongo , Bharat Ratra

We measure the current expansion rate of the Universe, Hubble's constant $H_0$, by calibrating the absolute magnitudes of supernovae to distances measured by Baryon Acoustic Oscillations. This `inverse distance ladder' technique provides an…

Weighted mean and median statistics techniques are used to combine 23 independent lower redshift, $z<1.04$, Hubble parameter, $H(z)$, measurements and determine binned forms of $H(z)$. When these are combined with 5 higher redshift,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Omer Farooq , Sara Crandall , Bharat Ratra

We investigate the properties of a cosmological scenario which undergoes a gravitational phase transition at late times. In this scenario, the Universe evolves according to general relativity in the standard, hot Big Bang picture until a…

Astrophysics · Physics 2013-05-29 Robert R. Caldwell , William Komp , Leonard Parker , Daniel A. T. Vanzella