Results 21 to 30 of about 7,610 (173)

On the initial singularity and extendibility of flat quasi-de Sitter spacetimes

Journal of High Energy Physics, 2023
Inflationary spacetimes have been argued to be past geodesically incomplete in many situations. However, whether the geodesic incompleteness implies the existence of an initial spacetime curvature singularity or whether the spacetime may be extended ...
Ghazal Geshnizjani, Eric Ling, Jerome Quintin   +2 more
doaj   +1 more source

Anisotropic solutions in symmetric teleparallel $$f\left( Q\right) $$ f Q -theory: Kantowski–Sachs and Bianchi III LRS cosmologies

European Physical Journal C: Particles and Fields, 2023
We investigate the existence of anisotropic self-similar exact solutions in symmetric teleparallel $$f\left( Q\right) $$ f Q -theory. For the background geometry we consider the Kantowski–Sachs and the Locally Rotationally Symmetric Bianchi type III ...
N. Dimakis, M. Roumeliotis, A. Paliathanasis, T. Christodoulakis   +3 more
doaj   +1 more source

Islands in the fluid: islands are common in cosmology

Journal of High Energy Physics, 2023
We discuss the possibility of entanglement islands in cosmological spacetimes with a general perfect fluid with an equation of state w. We find that flat universes with time-symmetric slices where the Hubble parameter vanishes always have islands on that
Ido Ben-Dayan, Merav Hadad, Elizabeth Wildenhain   +2 more
doaj   +1 more source

Ellipsoidal shapes in general relativity: general definitions and an application [PDF]

, 2003
A generalization of the notion of ellipsoids to curved Riemannian spaces is given and the possibility to use it in describing the shapes of rotating bodies in general relativity is examined.
Bradley M, Chandrasekhar S, Dyer C C, Ferwagner R, Gergely L Á, Geroch R, Geroch R, Herlt E, J zsef Zsigrai, Kramer D, Krasinski A, Lukács B, Maison D, Marklund M, Misner C, Musgrave P, Neugebauer G, Neugebauer G, Neugebauer G, Perjés Z, Rácz I, Rácz I, Rácz I, Rácz I, Stewart J M, Vacaru S I, Vacaru S I, Vacaru S I, Vacaru S I, Vacaru S I, Vacaru S I, Zsigrai J, Zsigrai J   +32 more
core   +3 more sources

Critical Robertson-Walker universes [PDF]

, 2019
The integral of the energy density function $\mathfrak m$ of a closed Robertson-Walker (RW) spacetime with source a perfect fluid and cosmological constant $\Lambda$ gives rise to an action functional on the space of scale functions of RW spacetime ...
Eshkobilov, Olimjon, Musso, Emilio, Nicolodi, Lorenzo   +2 more
core   +2 more sources

Cylindrical wormholes and electromagnetic field

Nuclear Physics B, 2023
In this manuscript, we study the construction of static cylindrically symmetric thin shell wormhole models with an electric charge in the background of f(R,T) gravity.
M. Yousaf, M.Z. Bhatti, Z. Yousaf
doaj   +1 more source

Gradient Ricci Bourguignon solitons on perfect fluid space-times [PDF]

Journal of Mahani Mathematical Research
The main purpose of the present paper is about characterizing the properties of the perfect fluid space-time that admits the gradient Ricci-Bourguignon soliton. This gives some results about the stability of the energy-momentum tensor and also under some
Sakineh Hajiaghasi, Shahroud Azami
doaj   +1 more source

Charged perfect fluid sphere in higher-dimensional spacetime [PDF]

Indian Journal of Physics, 2019
Present paper provides a new model for perfect fluid sphere filled with charge in higher dimensional spacetime admitting conformal symmetry. We consider a linear equation of state with coefficients fixed by the matching conditions at the boundary of the source corresponding to the exterior Reissner-Nordstr m higher dimensional spacetime.
P. Bhar, T. Manna, F. Rahaman, Saibal Ray, G. S. Khadekar   +4 more
openaire   +2 more sources

Some curvature properties of perfect fluid spacetimes

Quaestiones Mathematicae, 2023
In this paper we assume that a perfect fluid is the source of the gravitational field while analyzing the solutions to the Einstein field equations.
Krishnendu De, Uday Chand De, Ljubica S. Velimirovic   +2 more
openaire   +3 more sources

Exploring accelerating hairy black holes in 2+1 dimensions: the asymptotically locally anti-de Sitter class and its holography

Journal of High Energy Physics, 2023
In the realm of lower-dimensional accelerating spacetimes, it is well-established that the presence of domain walls, which are co-dimension one topological defects, is a necessary condition for their construction.
Adolfo Cisterna, Felipe Diaz, Robert B. Mann, Julio Oliva   +3 more
doaj   +1 more source