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We study a charged compact object with anisotropic pressures in a core envelope setting. The equation of state is quadratic in the core and linear in the envelope. There is smooth matching between the three regions: the core, envelope and…

General Relativity and Quantum Cosmology · Physics 2017-01-04 P. Mafa Takisa , S. D. Maharaj

Molecular clouds are supported by thermal pressure, magnetic pressure, and turbulent pressure. Each of these can be modeled with a polytropic equation of state, so that overall the total pressure is the sum of the individual components. We…

Astrophysics · Physics 2012-08-27 Christopher F. McKee , John H. Holliman , II

We study the gravitational vacuum star (gravastar) configuration as proposed by other authors in a model where the interior de Sitter spacetime segment is continuously extended to the exterior Schwarzschild spacetime. The multilayered…

General Relativity and Quantum Cosmology · Physics 2007-06-19 A. DeBenedictis , D. Horvat , S. Ilijic , S. Kloster , K. S. Viswanathan

In this article we study the expanding properties of random perturbations of contracting Lorenz maps satisfying the summability condition of exponent 1. Under general conditions on the maps and perturbation types, we prove stochastic…

Dynamical Systems · Mathematics 2026-04-10 Haoyang Ji

The main purpose of this paper is to capture the asymptotic behavior for solutions to a class of nonlinear elliptic and parabolic equations with the anisotropic weights consisting of two power-type weights of different dimensions near the…

Analysis of PDEs · Mathematics 2024-04-23 Changxing Miao , Zhiwen Zhao

General relativistic anisotropic fluid models whose fluid flow lines form a shear-free, irrotational, geodesic timelike congruence are examined. These models are of Petrov type D, and are assumed to have zero heat flux and an anisotropic…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Des J. Mc Manus , Alan A. Coley

We obtain conditions for the existence and stability of de Sitter attractors in the phase space of spatially homogeneous and isotropic cosmology in generalized theories of gravity (including non-linear and scalar-tensor theories). These…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Valerio Faraoni

We show that the inclusion of simple anisotropic pressures stops the isotropic Friedmann universe being a stable attractor as an initial or final singularity is approached when pressures can exceed the energy density. This shows that the…

General Relativity and Quantum Cosmology · Physics 2014-11-20 John D Barrow , Kei Yamamoto

Motivated by current searches for signals of Lorentz symmetry violation in nature and recent investigations on generalized uncertainty principle (GUP) models in anisotropic space, in this paper we identify GUP models satisfying two…

Quantum Physics · Physics 2023-05-22 André H. Gomes

The linear theory for rotating compressible convection in a plane layer geometry is presented for the astrophysically-relevant case of low Prandtl number gases. When the rotation rate of the system is large, the flow remains geostrophically…

Geophysics · Physics 2015-03-02 Michael A. Calkins , Keith Julien , Philippe Marti

Among systems that display generic scale invariance, those whose asymptotic properties are anisotropic in space (strong anisotropy, SA) have received a relatively smaller attention, specially in the context of kinetic roughening for…

Statistical Mechanics · Physics 2015-06-11 Edoardo Vivo , Matteo Nicoli , Rodolfo Cuerno

In this paper we analyze the conditions when the Einstein equations with cosmological constant and matter describe (2+1)-dimensional generic locally anisotropic (la) spacetimes of generalized Finsler type. New classes of solutions for such…

General Relativity and Quantum Cosmology · Physics 2009-09-25 Sergiu I. Vacaru

We derive a new interior solution for stellar compact objects in $f\mathcal{(R)}$ gravity assuming a differential relation to constrain the Ricci curvature scalar. To this aim, we consider specific forms for the radial component of the…

General Relativity and Quantum Cosmology · Physics 2021-06-03 G. G. L. Nashed , S. Capozziello

The standard cosmological model is challenged by an ever-growing collection of observations, which invites (and stimulates) inquiry into possible additions and/or alterations. One such alteration comes from letting cosmic isotropy -- as…

General Relativity and Quantum Cosmology · Physics 2026-04-22 Robbert W. Scholtens , Marcello Seri , Holger Waalkens , Rien van de Weygaert

We study the polytropic gas scenario as the unification of dark matter and dark energy. We fit the model parameters by using the latest observational data including type Ia supernovae, baryon acoustic oscillation, cosmic microwave…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-01 K. Karami , Z. Safari , S. Asadzadeh

In this paper, we generate an exact anisotropic gravastar model using gravitational decoupling technique through minimal geometric deformation in the framework of $f(\Re, {T}^{2})$ gravity. This novel model explains an ultra-compact stellar…

General Relativity and Quantum Cosmology · Physics 2023-04-17 M. Sharif , Saba Naz

Sought-after ordered structures of mixtures of hard anisotropic nanoparticles can often be thermodynamically unfavorable due to the components' geometric incompatibility to densely pack into regular lattices. A simple compatibilization rule…

Soft Condensed Matter · Physics 2014-10-22 Mihir R. Khadilkar , Fernando A. Escobedo

Polymer models are effective in describing quantum gravity effects around the initial singularity, leading to its replacement by bouncing surfaces on which the curvature and densities are finite. Their properties depend on the space-time…

General Relativity and Quantum Cosmology · Physics 2026-02-23 D. A. Cook , A. Olimpieri , I. P. R. Baranov , H. A. Borges , S. Carneiro

In this paper, we derive multiple anisotropic analogs from the established isotropic model by means of the gravitational decoupling approach in a fluid-geometry interaction based theory. To accomplish this, we initially consider a static…

General Relativity and Quantum Cosmology · Physics 2025-02-24 Tayyab Naseer , G. Mustafa

A new class of solutions to Einstein's classical field equations of general relativity is presented. The solutions describe a non-rotating, spherically symmetric, compact self gravitating object, residing in a static electro-vacuum space…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Michael Petri