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Related papers: Comment to ''On Anisotropic Dark Energy Stars''

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Negative energy scenarios are the most widely studied for the warp metric. In fact, the prevailing view in the community so far has been that the warp metric necessarily has negative energies. In this work it is shown that the issue of…

General Physics · Physics 2023-04-21 G. Abellan , N. Bolivar , I. Vasilev

A general formalism developed few years ago to model polytropic Newtonian stars with anisotropic pressure is applied to model stars for which, both, radial and tangential pressure satisfy polytropic equations of state. We obtain the…

General Relativity and Quantum Cosmology · Physics 2020-07-02 G. Abellan , E. Fuenmayor , L. Herrera

In this work, we have investigated anisotropic neutron stars in the framework of Rastall-Rainbow gravity. All our calculations were computed using the IU-FSU realistic equation of state (EoS), in which was considered two cases: standard…

High Energy Astrophysical Phenomena · Physics 2019-11-11 Clésio E. Mota , Luis C. N. Santos , Franciele M. da Silva , Cesar V. Flores , Tiago J. N. da Silva , Débora P. Menezes

We present a class of new relativistic solutions with anisotropic fluid for compact stars in hydrostatic equilibrium. The interior space-time geometry considered here for compact objects are described by parameters namely, $\lambda$, $k$,…

General Relativity and Quantum Cosmology · Physics 2016-03-25 Bikash Chandra Paul , Rumi Deb

A new class of solutions describing the composition of compact stars has been proposed, assuming that the fluid distribution inside the star is anisotropic. This is achieved by assuming the appropriate metric potential and then solving…

General Physics · Physics 2020-03-11 D. M. Pandya , B. Thakore , R. Goti , J. P. Rank , S. Shah

This paper explored the physical acceptability conditions for anisotropic matter configurations in General Relativity. The study considered a generalized polytropic equation of state $P=\kappa {\rho}^{\gamma}+\alpha \rho -\beta$ for a…

General Relativity and Quantum Cosmology · Physics 2022-03-14 Daniel Suárez-Urango , J. Ospino , Héctor Hernández , Luis A. Núñez

The surprising discovery of an accelerating universe led cosmologists to posit the existence of "dark energy"--a mysterious energy field that permeates the universe. Understanding dark energy has become the central problem of modern…

The authors respond to the commentary listed in the title.

Astrophysics · Physics 2007-05-23 Sebastien Fromang , Steven A. Balbus

In present paper a spherically symmetric stellar configuration has been analyzed by assuming the matter distribution of the stellar configuration is anisotropic in nature and compared with the realistic objects, namely, the low mass X-ray…

General Relativity and Quantum Cosmology · Physics 2021-08-26 Piyali Bhar , Tuhina Manna , Farook Rahaman , Ayan Banerjee

We use recent astrophysical and local tests of the stability of the fine-structure constant, $\alpha$, to constrain a particular phenomenological but physically motivated class of models in which the dark energy equation of state can…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-12 C. J. A. P. Martins , M. Prat Colomer

Recent observations of Type Ia supernova at high redshifts establish that the dark energy component of the universe has (a probably constant) ratio between pressure and energy density $w=p/\rho=-1.02(^{+0.13}_{-0.19})$. The conventional…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Edgard Gunzig , Alberto Saa

We study the dynamics of dark energy in the presence of a 2-form field coupled to a canonical scalar field $\phi$. We consider the coupling proportional to $e^{-\mu \phi/M_{\rm pl}} H_{\alpha \beta \gamma}H^{\alpha \beta \gamma}$ and the…

High Energy Physics - Theory · Physics 2019-09-25 Juan P. Beltrán Almeida , Alejandro Guarnizo , Ryotaro Kase , Shinji Tsujikawa , César A. Valenzuela-Toledo

In general relativity, for fluids with a linear equation of state (EoS) or scalar fields, the high isotropy of the universe requires special initial conditions, and singularities are anisotropic in general. In the brane world scenario…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Kishore N. Ananda , Marco Bruni

This correspondence delves into the application of dynamical systems methodologies within the context of cosmology, specifically addressing a preliminary strategy for determining the range for the equation of state for dark energy…

General Relativity and Quantum Cosmology · Physics 2025-09-10 Bob Osano

Some cosmological scenarios with bulk viscosity for the dark energy fluid are considered. Based on some considerations related to hydrodynamics, two different equations of state for dark energy are assumed, leading to power-law and…

General Relativity and Quantum Cosmology · Physics 2020-02-07 Sergei D. Odintsov , Diego Saez-Chillon Gomez , German S. Sharov

We present a class of exact solutions of Einstein's gravitational field equations describing spherically symmetric and static anisotropic stellar type configurations. The solutions are obtained by assuming a particular form of the…

General Relativity and Quantum Cosmology · Physics 2009-11-07 M. K. Mak , T. Harko

In this study we explore the astrophysical implications of pressure anisotropy on the physical characteristics of millisecond pulsars within the framework of $f(Q)$ gravity, {in particular $f(Q)=-\alpha\, Q - \beta$, where $\alpha$ and…

General Relativity and Quantum Cosmology · Physics 2024-10-08 S. K. Maurya , Ksh. Newton Singh , G. Mustafa , M. Govender , Abdelghani Errehymy , Abdul Aziz

Through the geodesic analysis of a static and axially symmetric space time, we present conditions on the state equation of an isotropic perfect fluid $p=\omega d$, when it is considered as dark matter in spiral galaxies. The main conclusion…

Astrophysics · Physics 2007-05-23 F. Siddhartha Guzman , Tonatiuh Matos , Dario Nunez , Erandy Ramirez

Non-radial oscillation modes of neutron stars serve as diagnostics of their internal composition and relativistic structure. In this work, we investigate the perturbations of static and spherically symmetric neutron stars characterized by…

General Relativity and Quantum Cosmology · Physics 2026-05-08 Jose F. Rodriguez-Ruiz , L. M. Becerra , F. D. Lora-Clavijo

By introducing the polytropic gas model of interacting dark energy, we obtain the equation of state for the polytropic gas energy density in a non-flat universe. We show that for even polytropic index by choosing $K>Ba^{\frac{3}{n}}$, one…

General Relativity and Quantum Cosmology · Physics 2014-11-20 K. Karami , S. Ghaffari , J. Fehri