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The thermal view of scalar-tensor gravity is an analogy with a dissipative fluid. The scalar degree of freedom excites gravity to a positive ``temperature'', while Einstein gravity is the ``zero-temperature'' equilibrium state. We extend…

General Relativity and Quantum Cosmology · Physics 2025-07-22 Valerio Faraoni

We investigate the gravitational collapse of a spherically symmetric, inhomogeneous star, which is described by a perfect fluid with heat flow and satisfies the equation of state $p=\rho/3$ at its center. In the process of the gravitational…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Zhe Chang , Cheng-Bo Guan , Chao-Guang Huang , Xin Li

We provide a new class of interior solutions for anisotropic stars admitting conformal motion. The Einstein's field equations in this construction are solved for specific choices of the density/mass functions. We analyze the behavior of the…

General Relativity and Quantum Cosmology · Physics 2010-11-03 Farook Rahaman , Mubasher Jamil , Ranjan Sharma , Kausik Chakraborty

We present a class of singularity free exact cosmological solutions of Einstein's equations describing a perfect fluid with heat flow. It is obtained as generalization of the Senovilla class [1] corresponding to incoherent radiation field.…

General Relativity and Quantum Cosmology · Physics 2010-04-06 L. K. Patel , Naresh Dadhich

In this paper, we have discussed the gravitational collapse and expansion of charged anisotropic cylindrically symmetric gravitating source. To this end, the generating solutions of Einstein-Maxwell field equations for the given source and…

General Physics · Physics 2015-04-22 T. Mahmood , S. M. Shah , G. Abbas

Using the Sparling form and a geometric construction adapted to spacetimes with a 2-dimensional isometry group, we analyse a quasi-local measure of gravitational energy. We then study the gravitational radiation through spacetime junctions…

General Relativity and Quantum Cosmology · Physics 2018-11-27 Alfonso García-Parrado , Filipe C. Mena

We expand previous work on an inverse approach to Einstein Field Equations where we include fluids with energy flux and consider the vanishing of the anisotropic stress tensor. We consider the approach using warped product spacetimes of…

General Relativity and Quantum Cosmology · Physics 2011-02-01 James Richardson , Mustapha Ishak

We present the interior solution for a static, spherically symmetric perfect fluid star backreacted by QFT in four dimensions invoking no arbitrary parameters. It corresponds to a constant energy density star and is fully non-perturbative.…

General Relativity and Quantum Cosmology · Physics 2025-01-20 Pietro Paolo Melella , Ignacio A. Reyes

In this article, we present a class of relativistic solutions describing spherically symmetric and static anisotropic stars in hydrostatic equilibrium. For this purpose, we consider a particularized matric potential, namely, Buchdahl ansatz…

General Relativity and Quantum Cosmology · Physics 2021-08-03 S. K. Maurya , Ayan Banerjee , M. K. Jasim , J. Kumar , A. K. Prasad , Anirudh Pradhan

The properties of an anisotropic fluid outside a star or a black hole embedded in an expanding universe are investigated. One finds that, in Painleve-Gullstrand coordinates, the heat flux of the cosmological fluid vanishes, in spite of the…

General Relativity and Quantum Cosmology · Physics 2012-03-21 Hristu Culetu

We study the gravitational behaviour of a spherically symmetric radiating star when the fluid particles are in geodesic motion. We transform the governing equation into a simpler form which allows for a general analytic treatment. We find…

General Relativity and Quantum Cosmology · Physics 2009-11-13 S. Thirukkanesh , S. D. Maharaj

Analytic gravitational collapse and expansion solutions with anisotropic pressure are generated. Metric functions are found by requiring zero heat flow scalar. It emerges that a single function generates the anisotropic solutions. Each…

General Relativity and Quantum Cosmology · Physics 2013-09-30 E. N. Glass

We consider a spherically symmetric stellar model in general relativity whose interior consists of a pressureless fluid undergoing microscopic velocity diffusion in a cosmological scalar field. We show that the diffusion dynamics compel the…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Artur Alho , Simone Calogero

New exact interior solutions to the Einstein field equations for anisotropic spheres are found. We utilise a procedure that necessitates a choice for the energy density and the radial pressure. This class contains the constant density model…

General Relativity and Quantum Cosmology · Physics 2009-11-11 M. Chaisi , S. D. Maharaj

The symmetry method is used to derive solutions of Einstein's equations for fluid spheres using an isotropic metric and a velocity four vector that is non-comoving. Initially the Lie, classical approach is used to review and provide a…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Ron Wiltshire

We review the matching conditions for a collapsing anisotropic cylindrical perfect fluid, recently discussed in the literature (2005 {\it Class. Quantum Grav.} {\bf 22} 2407). It is shown that radial pressure vanishes on the surface of the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 L. Herrera , M. A. H. MacCallum , N. O. Santos

We start with a recently introduced spherically symmetric geodesic fluid model (arXiv: 1601.07030) whose energy-momentum tensor in the comoving frame is dust-like with nontrivial energy flux. In the non-comoving energy frame (vanishing…

General Physics · Physics 2018-02-14 Peter C. Stichel

We analyze several spherically symmetric exterior vacuum solutions allowed by the Einstein-Aether (EA) theory with a non static aether and study the thermodynamics of their Killing and universal horizons. We show that there are five classes…

General Relativity and Quantum Cosmology · Physics 2022-11-09 R. Chan , M. F. A. da Silva , V. H. Satheeshkumar

This paper investigates the evolution of collapsing FRW models with a scalar field having the potential which arises in the conformal frame of high order gravity theories, coupled to matter described by a perfect fluid with energy density…

General Relativity and Quantum Cosmology · Physics 2010-03-24 Roberto Giambò

In the presence of a minimal length physical objects cannot collapse to an infinite density, singular, matter point. In this note we consider the possible final stage of the gravitational collapse of "thick" matter layers. The energy…

General Relativity and Quantum Cosmology · Physics 2013-12-24 Piero Nicolini , Alessio Orlandi , Euro Spallucci
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