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Within the context of a cosmic space whose energy source is modeled with a perfect fluid, a uniform model of Universe based on a standard FRW cosmology containing decoupled mixed matter sources namely stiff matter and cosmic dust together…

General Relativity and Quantum Cosmology · Physics 2016-09-07 Denisa-Andreea Mihu

We investigate exact solutions of the Einstein-Maxwell equations with the cosmological constant where the source of the gravitational field consists of a magnetic field and dust. In particular, we restrict our study to the case of Bianchi…

General Relativity and Quantum Cosmology · Physics 2025-05-23 Martin Zofka , Kjell Rosquist

In this paper, we study short-time existence of static flow on complete noncompact asymptotically static manifolds from the point of view that the stationary points of the evolution equations can be interpreted as static solutions of the…

Differential Geometry · Mathematics 2015-05-30 Xue Hu , Yuguang Shi

We show that there exist asymptotically flat almost-smooth initial data for Einstein-perfect fluid's equation that represent an isolated liquid-type body. By liquid-type body we mean that the fluid energy density has compact support and…

General Relativity and Quantum Cosmology · Physics 2011-04-21 Sergio Dain , Gabriel Nagy

In this article, we investigate the impact of cosmological parameters on black holes using an exact solution to Einstein's equations that satisfies the Whittaker equation of state. We examine a spherically symmetric black hole in the…

General Relativity and Quantum Cosmology · Physics 2024-04-26 Santanu Tripathy , K Rajesh Nayak

In this paper we performed investigation of the spatially-flat cosmological models whose spatial section is product of three- ("our Universe") and extra-dimensional parts. The matter source chosen to be the perfect fluid which exists in the…

General Relativity and Quantum Cosmology · Physics 2019-02-11 Sergey A. Pavluchenko

Assuming conformally flat metric we obtain inhomogeneous solutions of Einstein equations with the energy-momentum of a viscous fluid. We suggest that the viscous solution can be applied as a model of an expanding inhomogeneous dark energy.

General Relativity and Quantum Cosmology · Physics 2020-03-31 Z. Haba

We present a flat (K=0) cosmological model, described by a perfect fluid with the ``constants'' $G,c$ and $\Lambda$ varying with cosmological time $t$. We introduce Planck\'s ``constant'' $\hbar$ in the field equations through the equation…

General Relativity and Quantum Cosmology · Physics 2009-11-10 José Antonio Belinchón , Antonio Alfonso-Faus

We investigate static spherically symmetric perfect fluid models in Newtonian gravity for barotropic equations of state that are asymptotically polytropic at low and high pressures. This is done by casting the equations into a 3-dimensional…

Astrophysics · Physics 2009-11-07 J. Mark Heinzle , Claes Uggla

We consider ideal fluid and equivalent scalar field dark energy universes where all four known types of finite-time, future singularities occur at some parameter values. It is demonstrated that pressure/energy density of such…

High Energy Physics - Theory · Physics 2015-05-13 Shin'ichi Nojiri , Sergei D. Odintsov

The stability properties of the Einstein Static solution of General Relativity are altered when corrective terms arising from modification of the underlying gravitational theory appear in the cosmological equations. In this paper the…

General Relativity and Quantum Cosmology · Physics 2014-11-21 Rosangela Canonico , Luca Parisi

We obtain a new class of rotating black holes for Einstein theory with perfect fluid source in (2+1) dimensions. We conclude that these black hole solutions only depend on variable angular velocity $m(r)$. Some examples of these black holes…

General Relativity and Quantum Cosmology · Physics 2014-08-19 Bin Wu , Wei Xu

We consider self-gravitating fluids in cosmological spacetimes with Gowdy symmetry on the torus $T^3$ and, in this class, we solve the singular initial value problem for the Einstein-Euler system of general relativity, when an initial data…

General Relativity and Quantum Cosmology · Physics 2017-12-11 Florian Beyer , Philippe G. LeFloch

We derive the basic equations of the cosmological first-order post-Newtonian approximation from the recently formulated fully nonlinear and exact cosmological perturbation theory in Einstein's gravity. Apparently the latter, being exact,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Hyerim Noh , Jai-chan Hwang

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 study the Einstein field equations for spacetimes admitting a maximal two-dimensional abelian group of isometries acting orthogonally transitively on spacelike surfaces and, in addition, with at least one conformal Killing vector. The…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Marc Mars , Thomas Wolf

We demonstrate that the thermodynamics of a perfect fluid describing baryonic matter can, in certain limits, lead to an equation of state similar to that of dark energy. We keep the cosmic fluid equation of state quite general by just…

General Relativity and Quantum Cosmology · Physics 2021-01-26 Georgios Lukes-Gerakopoulos , Giovanni Acquaviva , Charalampos Markakis

We construct exact static inhomogeneous solutions to Einstein's equations with counter flow of particle fluid and a positive cosmological constant by using the Sasaki metrics on three-dimensional spaces. The solutions, which admit an…

High Energy Physics - Theory · Physics 2022-03-23 Hideki Ishihara , Satsuki Matsuno

In this work, we have obtained exact solutions of Einstein equations for static and axially symmetric magnetized matter, specifically in plane-symmetric and almost-plane symmetric cases. Although these solutions impose constraints on the…

General Relativity and Quantum Cosmology · Physics 2018-04-05 Ernesto Contreras , Pedro Bargueno , Gretel Quintero , Aurora Perez-Martinez , Diana Alvear

We investigate newtonian description of accreting compact bodies with hard surfaces, including luminosity and selfgravitation of polytropic perfect fluids. This nonlinear integro-differential problem reduces, under appropriate boundary…

Astrophysics · Physics 2007-05-23 Janusz Karkowski , Edward Malec , Krzysztof Roszkowski