Results 1 to 10 of about 18,336 (194)

Perfect Fluid Spacetimes and Gradient Solitons

Journal of Nonlinear Mathematical Physics, 2022
AbstractIn this article, we investigate perfect fluid spacetimes equipped with concircular vector field. At first, in a perfect fluid spacetime admitting concircular vector field, we prove that the velocity vector field annihilates the conformal curvature tensor.
Krishnendu De, Uday Chand De, Abdallah Abdelhameed Syied, Nasser Bin Turki, Suliman Alsaeed   +4 more
exaly   +5 more sources

Static and stationary dark fluid universes: a gravitoelectromagnetic perspective [PDF]

Scientific Reports, 2022
The usual characterization of exact solutions of Einstein field equations, including cosmological solutions, is based on the symmetry properties of their corresponding metrics which is obviously mathematically involved.
M. Nouri-Zonoz, A. Nourizonoz
doaj   +2 more sources

Characterizations of generalized Robertson-Walker spacetimes concerning gradient solitons [PDF]

Heliyon
In this article, we examine gradient type Ricci solitons and (m,τ)-quasi Einstein solitons in generalized Robertson-Walker (GRW) spacetimes. Besides, we demonstrate that in this scenario the GRW spacetime presents the Robertson-Walker (RW) spacetime and ...
Krishnendu De, Mohammad Nazrul Islam Khan, Uday Chand De   +2 more
doaj   +2 more sources

Classification of LRS Bianchi-I spacetime in context of f(T) gravity via its self-similar symmetry. [PDF]

PLoS ONE
This study investigates self-similar vector fields of locally rotationally symmetric Bianchi type-I spacetimes within the framework of f(T) gravity, incorporating a perfect fluid as the matter source.
Rabeb Sidaoui, A H A Alfedeel, Jamshed Khan, Mohammed Alsharafi, E I Hassan, Khaled Aldwoah   +5 more
doaj   +2 more sources

ON THE POST-LINEAR QUADRUPOLE-QUADRUPOLE METRIC

Revista de Matemática: Teoría y Aplicaciones, 2017
The Hartle-Thorne metric defines a reliable spacetime for most astrophysical purposes, for instance simulations of slowly rotating stars. Solving the Einstein field equations, we added terms of second order in the quadrupole moment to its post-linear ...
FRANCISCO FRUTOS ALFARO, MICHAEL SOFFEL
doaj   +4 more sources

Novel Theorems on Spacetime Admitting Pseudo-W2 Curvature Tensor

Journal of Mathematics
This paper investigates spacetime manifolds admitting a pseudo-W2 curvature tensor. We show that a pseudo-W2 flat spacetime is an Einstein manifold and therefore has constant curvature.
B. B. Chaturvedi, Prabhawati Bhagat, Mohammad Nazrul Islam Khan   +2 more
doaj   +2 more sources

The Covariant Approach to LRS Perfect Fluid Spacetime Geometries [PDF]

Classical and Quantum Gravity, 1995
The dynamics of perfect fluid spacetime geometries which exhibit {\em Local Rotational Symmetry} (LRS) are reformulated in the language of a $1+\,3$ "threading" decomposition of the spacetime manifold, where covariant fluid and curvature variables are ...
Bondi H, Bonnor W B, Bradley M, Collins C B, Collins C B, Cotton E, Ehlers J, Ehlers J, Eisenhart L P, Ellis G F R, Ellis G F R, Ellis G F R, Ellis G F R, Farnsworth D L, George F R Ellis, Henk van Elst, Hsu L, Jantzen R T, Kantowski R, King A R, Kramer D, Krasinski A, Lemaître G, Longair M S, MacCallum M A H, MacCallum M A H, Misner C W, Schouten J A, Shapiro S L, Stephani H, Stewart J M, Tolman R C, Wainwright J, Wainwright J   +33 more
core   +3 more sources

Navigating Dementia: Political Materialities of Public Transport in the All-Ageing Metropolis. [PDF]

Sociol Health Illn
ABSTRACT Age‐ and dementia‐friendliness are major areas of contemporary urban policy and scholarship, seeking to maintain older people and those with cognitive impairment in their own homes and communities. Such work relies on architectural augmentation to maximise the functionality of ageing bodies and minds and has been criticised for conceptualising
Fletcher JR.
europepmc   +2 more sources

Conharmonic Curvature Inheritance in Spacetime of General Relativity

Universe, 2021
The motive of the current article is to study and characterize the geometrical and physical competency of the conharmonic curvature inheritance (Conh CI) symmetry in spacetime.
Musavvir Ali, Mohammad Salman, Mohd Bilal   +2 more
doaj   +1 more source

Conformally Flat Pseudoprojective Symmetric Spacetimes in fR,G Gravity

Advances in Mathematical Physics, 2022
Sufficient conditions on a pseudoprojective symmetric spacetime  PPSn whose Ricci tensor is of Codazzi type to be either a perfect fluid or Einstein spacetime are given.
Uday Chand De, Sameh Shenawy, Abdallah Abdelhameed Syied, Nasser Bin Turki   +3 more
doaj   +1 more source