Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

Article Types

Countries / Regions

Search Results (2)

Search Parameters:
Keywords = LTB spacetimes

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
12 pages, 302 KiB  
Article
Noether Symmetries of Lemaitre-Tolman-Bondi Metric via Rif Tree Approach
by Muhammad Farhan, Tahir Hussain, Nabil Mlaiki and Aiman Mukheimer
Symmetry 2022, 14(9), 1864; https://doi.org/10.3390/sym14091864 - 7 Sep 2022
Cited by 3 | Viewed by 1689
Abstract
In this paper, we have explored Noether symmetries for the Lagrangian corresponding to the Lemaitre-Tolman-Bondi (LTB) spacetime metric via a Rif tree approach. Instead of the frequently used method of directly integrating the Noether symmetry equations, a MAPLE algorithm is used to convert [...] Read more.
In this paper, we have explored Noether symmetries for the Lagrangian corresponding to the Lemaitre-Tolman-Bondi (LTB) spacetime metric via a Rif tree approach. Instead of the frequently used method of directly integrating the Noether symmetry equations, a MAPLE algorithm is used to convert these equations to the reduced involutive form (Rif). The interesting feature of this algorithm is that it provides all possible metrics admitting different dimensional Noether symmetries. These metrics are given in the form of branches of a tree, known as a Rif tree. These metrics are used to solve the determining equations and the explicit form of symmetry vector fields are found, giving 4, 5, 6, 7, 8, 9, 11, and 17-dimensional Noether algebras. To add some physical implications, Einstein’s field equations are used to find the stress-energy tensor for all the explicitly known metrics, and the parameters appearing in the metrics are used to find bounds for different energy conditions. Full article
(This article belongs to the Special Issue Noether and Space-Time Symmetries in Physics)
Show Figures

Figure 1

17 pages, 315 KiB  
Article
Hyperbolically Symmetric Versions of Lemaitre–Tolman–Bondi Spacetimes
by Luis Herrera, Alicia Di Prisco and Justo Ospino
Entropy 2021, 23(9), 1219; https://doi.org/10.3390/e23091219 - 16 Sep 2021
Cited by 17 | Viewed by 2042
Abstract
We study fluid distributions endowed with hyperbolic symmetry, which share many common features with Lemaitre–Tolman–Bondi (LTB) solutions (e.g., they are geodesic, shearing, and nonconformally flat, and the energy density is inhomogeneous). As such, they may be considered as hyperbolic symmetric versions of LTB, [...] Read more.
We study fluid distributions endowed with hyperbolic symmetry, which share many common features with Lemaitre–Tolman–Bondi (LTB) solutions (e.g., they are geodesic, shearing, and nonconformally flat, and the energy density is inhomogeneous). As such, they may be considered as hyperbolic symmetric versions of LTB, with spherical symmetry replaced by hyperbolic symmetry. We start by considering pure dust models, and afterwards, we extend our analysis to dissipative models with anisotropic pressure. In the former case, the complexity factor is necessarily nonvanishing, whereas in the latter cases, models with a vanishing complexity factor are found. The remarkable fact is that all solutions satisfying the vanishing complexity factor condition are necessarily nondissipative and satisfy the stiff equation of state. Full article
(This article belongs to the Special Issue Complexity of Self-Gravitating Systems)
Back to TopTop