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Rastall's theory belongs to the class of non-conservative theories of gravity. In vacuum, the only non-trivial static, spherically symmetric solution is the Schwarzschild one, except in a very special case. When a canonical scalar field is…

General Relativity and Quantum Cosmology · Physics 2017-03-03 K. A. Bronnikov , J. C. Fabris , O. F. Piattella , E. C. Santos

In this article, using gravitational decoupling by means of minimal geometric deformation approach, we obtain a new spherically symmetric and static black hole solution. To progress, we close the system by assuming that the average pressure…

General Relativity and Quantum Cosmology · Physics 2023-08-25 Francisco Tello-Ortiz , Ángel Rincón , A. Alvarez , Saibal Ray

We consider novel wormhole solutions supported by a matter content that minimally violates the null energy condition. More specifically, we consider an equation of state in which the sum of the energy density and radial pressure is…

General Relativity and Quantum Cosmology · Physics 2014-11-10 Mariam Bouhmadi-Lopez , Francisco S. N. Lobo , Prado Martin-Moruno

Recently, a modified theory of gravity was presented, which consists of the superposition of the metric Einstein-Hilbert Lagrangian with an $f(\cal R)$ term constructed \`{a} la Palatini. The theory possesses extremely interesting features…

General Relativity and Quantum Cosmology · Physics 2012-12-20 Salvatore Capozziello , Tiberiu Harko , Tomi S. Koivisto , Francisco S. N. Lobo , Gonzalo J. Olmo

An attempt has been made to have an analytical description for possible traversable wormhole in non-static spherically symmetric space-time supported by anisotropic fluid. Both trivial and non-trivial choices of the red-shift function…

General Relativity and Quantum Cosmology · Physics 2024-09-04 Subenoy Chakraborty , Madhukrishna Chakraborty

We build five-dimensional spherically symmetric wormholes within the DGP theory. We calculate the energy localized on the shell, and we find that the wormholes could be supported by matter not violating the energy conditions. We also show…

General Relativity and Quantum Cosmology · Physics 2010-09-07 Martín G. Richarte

In this work, we undertake an analysis of new wormhole solutions within an action-dependent Lagrangian framework. These geometries can be traversable and supported by a positive energy density. The modification of the gravitational field…

General Relativity and Quantum Cosmology · Physics 2024-06-12 Ismael Ayuso , Ruth Lazkoz

The Event Horizon Telescope (EHT) has recently observed the image and shadow of the supermassive compact object Sagittarius A$^*$ (Sgr A$^*$). According to the EHT collaboration, the observed image is consistent with the expected appearance…

General Relativity and Quantum Cosmology · Physics 2023-05-29 Rajibul Shaikh

We investigate the observable signatures -- the shadow, the throat silhouette, and the image of a thin accretion disk -- for a family of static, spherically symmetric wormholes with an arbitrary throat profile. First, we derive expressions…

General Relativity and Quantum Cosmology · Physics 2026-05-20 Valeria A. Ishkaeva , Sergey V. Sushkov

We reconstruct a static and spherically symmetric black hole geometry originally proposed as an effective metric by identifying a consistent matter source derived from a fundamental action. The space-time is supported by a magnetically…

The so-called hybrid metric-Palatini theory of gravity (HMPG), proposed in 2012 by T. Harko et al., is known to successfully describe both local (solar-system) and cosmological observations. This paper gives a complete description of…

General Relativity and Quantum Cosmology · Physics 2020-10-20 K. A. Bronnikov

We study traversable wormhole solutions in pure gauged $N\!=\!2$ supergravity with and without electromagnetic fields, which are locally isometric under $\mathrm{SO}(2,1)\!\times\!\mathrm{SO}(1,1)$. The model allows for 1/2-BPS wormhole…

High Energy Physics - Theory · Physics 2020-10-28 Andres Anabalon , Bernard de Wit , Julio Oliva

Investigations of shadows of astrophysical entities constitute a major source of insight into the evolution of compact objects. Such effects depend on the nature of the compact object and arise on account of the strong gravitational lensing…

General Relativity and Quantum Cosmology · Physics 2019-10-21 Muhammed Amir , Kimet Jusufi , Ayan Banerjee , Sudan Hansraj

An analytical solution representing traversable asymptotically flat and symmetric wormholes was obtained without adding exotic matter in two different theories independently: in the Einstein-Maxwell-Dirac theory and in the second…

General Relativity and Quantum Cosmology · Physics 2021-10-08 M. S. Churilova , R. A. Konoplya , Z. Stuchlik , A. Zhidenko

We study the problem of existence of static spherically symmetric wormholes supported by the kink-like configuration of a scalar field. With this aim we consider a self-consistent, real, nonlinear, nonminimally coupled scalar field $\phi$…

General Relativity and Quantum Cosmology · Physics 2009-11-07 S. V. Sushkov , S. -W. Kim

The compact dark objects with very large masses residing at the centres of galaxies are believed to be black holes. Due to the gravitational lensing effect, they would cast a shadow larger than their horizon size over the background, whose…

Astrophysics · Physics 2008-11-26 Lei Huang , Mike Cai , Zhi-Qiang Shen , Feng Yuan

This paper discusses a new wormhole solution that admits conformal motion, given a noncommutative-geometry background. After a discussion of the wormhole geometry and the energy conditions, the analysis proceeds with the calculation of the…

General Physics · Physics 2015-06-16 Farook Rahaman , Saibal Ray , G. S. Khadekar , P. K. F. Kuhfittig , Indrani Karar

The paper deals with static traversable wormhole having shape function a polynomial of the radial coordinate of degree 2. Embedding of the wormholes in space-time is examined both analytically and graphically. Also both timelike and null…

General Relativity and Quantum Cosmology · Physics 2021-12-03 Bikram Ghosh , Sourav Dutta , Sudeshna Mukerji , Subenoy Chakraborty

Quadratic gravity constitutes a prototypical example of a perturbatively renormalizable quantum theory of the gravitational interactions. In this work, we construct the associated phase space of static, spherically symmetric, and…

General Relativity and Quantum Cosmology · Physics 2023-05-10 Jesse Daas , Kolja Kuijpers , Frank Saueressig , Michael F. Wondrak , Heino Falcke

In this paper, we use the embedding class-I technique to examine the effect of charge on traversable wormhole geometry in the context of $f(\mathcal{G})$ theory, where $\mathcal{G}$ is the Gauss-Bonnet term. For this purpose, we consider…

General Relativity and Quantum Cosmology · Physics 2024-03-04 M. Zeeshan Gul , M. Sharif