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In this work, we consider time-dependent dark energy star models, with an evolving parameter $\omega$ crossing the phantom divide, $\omega=-1$. Once in the phantom regime, the null energy condition is violated, which physically implies that…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Andrew DeBenedictis , Remo Garattini , Francisco S. N. Lobo

This review on dark energy is intended for a wider audience, beginners as well as experts. It contains important notes on various aspects of dark energy and its alternatives. The section on Newtonian cosmology followed by heuristic…

High Energy Physics - Theory · Physics 2009-09-26 M. Sami

Modified teleparallel gravity theory with the torsion scalar have recently gained a lot of attention as a possible explanation of dark energy. We perform a thorough reconstruction analysis on the so-called $F(T)$ models, where $F(T)$ is…

General Physics · Physics 2012-11-13 Ratbay Myrzakulov

We study the $(w_0, \, w_a)$ parametrization of the dark energy (DE) equation of state, with and without the effective field theory of dark energy (EFTofDE) framework to describe the DE perturbations, parametrized here by the braiding…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-19 Zhiyu Lu , Théo Simon

The understanding of stellar structure represents the crossroads of our theories of the nuclear force and the gravitational interaction under the most extreme conditions observably accessible. It provides a powerful probe of the strong…

General Relativity and Quantum Cosmology · Physics 2020-09-15 Gonzalo J. Olmo , Diego Rubiera-Garcia , Aneta Wojnar

Alternative gravity theory is currently an incredibly significant technique for addressing some enduring experimental difficulties, such as the universe's dark region. They may also be employed in celestial cosmology, producing results that…

General Relativity and Quantum Cosmology · Physics 2024-05-01 Tayyaba Naz , Adnan Malik , Zenab Ramay

The modified F(R)-scalar-Gauss-Bonnet gravity is proposed as dark energy model. The reconstruction program for such theory is developed. It is explicitly demonstrated that the known classical universe expansion history (deceleration epoch,…

High Energy Physics - Theory · Physics 2008-11-26 Shin'ichi Nojiri , Sergei D. Odintsov , Petr V. Tretyakov

In this paper, we examine the acceleration of the Universe's expansion in $F(R,T)$ gravity, where $R$ denotes the Ricci scalar and $T$ the trace of energy-momentum tensor. Indeed, the unknown nature of the source controlling this…

General Relativity and Quantum Cosmology · Physics 2024-04-25 Ahmed Errahmani , Amine Bouali , Safae Dahmani , Imad El Bojaddaini , Taoufik Ouali

This work examines an early dark energy (EDE) scenario in the context of $F(R)$ gravity. EDE is introduced to alleviate the Hubble tension by temporarily injecting approximately $10\%$ of the energy fraction around the matter-radiation…

General Relativity and Quantum Cosmology · Physics 2026-04-21 Hua Chen , Taishi Katsuragawa , Shin'ichi Nojiri , Taotao Qiu

Within the framework of modified gravity model namely Slotheon model, inspired by the theory of extra dimensions, we explore the behaviour of Dark Energy and the perturbations thereof. The Dark Energy and matter perturbations equations are…

General Relativity and Quantum Cosmology · Physics 2020-07-15 Upala Mukhopadhyay , Debasish Majumdar , Debabrata Adak

We review theoretical developments in studies of dense matter and its phase structure of relevance to compact stars. Observational data on compact stars, which can constrain the properties of dense matter, are presented critically and…

Astrophysics · Physics 2008-11-26 Dany Page , Sanjay Reddy

In order to derive model-independent observational bounds on dark energy/modified gravity theories, a typical approach is to constrain parametrised models intended to capture the space of dark energy theories. Here we investigate in detail…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-03 Neel Shah , Kazuya Koyama , Johannes Noller

In this paper we propose a new dark energy model in the teleparallel alternative of general relativity, by considering a generalized non--minimal coupling of a tachyonic scalar field with the teleparallel boundary term. Within the framework…

General Relativity and Quantum Cosmology · Physics 2019-04-15 Sebastian Bahamonde , Mihai Marciu , Jackson Levi Said

We study the impact of bosonic, self-interacting dark matter on structural properties and tidal deformabilities of compact stars. As far as the gravitational theory is concerned, we assume Einstein's gravity in four dimensions with a…

General Relativity and Quantum Cosmology · Physics 2025-06-24 Takol Tangphati , Grigoris Panotopoulos , Ayan Banerjee , Anirudh Pradhan

This paper's main aim is to investigate the existence of a new classification of embedded class-I solutions of compact stars, by using Karmarkar condition in $f(R)$ gravity background. To achieve that goal, we consider two different models…

General Relativity and Quantum Cosmology · Physics 2021-05-07 Tayyaba Naz , Ammara Usman , M. Farasat Shamir

Conformal symmetries appear in many parts of physics and play a unique role in exploring the Universe. In this work, we consider the possibility of constructing conformal theories of gravity in the Symmetric Teleparallel Gravity framework,…

General Relativity and Quantum Cosmology · Physics 2020-03-18 Viktor Gakis , Martin Krššák , Jackson Levi Said , Emmanuel N. Saridakis

Modified gravity is one of the most favorable candidates for explaining the current accelerating expansion of the Universe. In this regard, we study the viability of an alternative gravitational theory, namely $f(R,G)$, by imposing energy…

General Relativity and Quantum Cosmology · Physics 2014-01-30 K. Atazadeh , F. Darabi

We study the effect of electric charge in compact stars assuming that the charge distribution is proportional to the mass density. The pressure and the density of the matter inside the stars are large, and the gravitational field is…

We propose the simplest model of teleparallel dark energy with purely a non-minimal coupling to gravity but no self-potential, a single model possessing various interesting features: simplicity, self-potential-free, the guaranteed late-time…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Je-An Gu , Chung-Chi Lee , Chao-Qiang Geng

We study the impact of asymmetric bosonic dark matter on neutron star properties, including possible changes of tidal deformability, maximum mass, radius, and matter distribution inside the star. The conditions at which dark matter…

High Energy Astrophysical Phenomena · Physics 2023-01-11 Violetta Sagun , Edoardo Giangrandi , Oleksii Ivanytskyi , Costança Providência , Tim Dietrich