Results 31 to 40 of about 59,420 (206)

Cosmological Perturbations from Cosmic Strings [PDF]

, 1994
Some aspects of the theory of cosmological perturbations from cosmic strings and other topological defects are outlined, with particular reference to a simple example: a spatially flat CDM-dominated universe.
Albrecht, Albrecht, Austin, Bennett, Coulson, Hindmarsh, Kolb, M. Hindmarsh, Pen, Sakellariadou, Shellard, Smith, Veeraraghavan, Vilenkin, Weinberg, White   +15 more
core   +3 more sources

ONE-DIMENSIONAL SIMULATIONS OF INHOMOGENEITY GROWTH IN PRESSURELESS GRAVITATING MATTER

Odessa Astronomical Publications, 2013
We study a model of the inhomogene­ity growth in the Universe filled with a pressureless matter. The standard hydrodynamical equations for the cosmological perturbations in the comoving frame are treated taking into account all nonlinear terms.
V. I. Zhdanov, V. M. Sliusar
doaj   +1 more source

Nonconservative unimodular gravity: a viable cosmological scenario?

European Physical Journal C: Particles and Fields, 2022
In this work we review the issue of imposing the conservation of the energy–momentum tensor as a necessary condition to recover the equivalence between the unimodular gravity and General Relativity (GR) equipped with a cosmological constant.
Júlio C. Fabris, Marcelo H. Alvarenga, Mahamadou Hamani-Daouda, Hermano Velten   +3 more
doaj   +1 more source

Cosmological Perturbations via Quantum Corrections in M-Theory

Universe, 2021
In the early universe, it is important to take into account the quantum effect of gravity to explain the feature of inflation. In this paper, we consider the M-theory effective action which consists of 11-dimensional supergravity and (Weyl)4 terms.
Kazuho Hiraga, Yoshifumi Hyakutake
doaj   +1 more source

Brane World Cosmological Perturbations

, 2004
We consider a brane world and its gravitational linear perturbations. We present a general solution of the perturbations in the bulk and find the complete perturbed junction conditions for generic brane dynamics. We also prove that (spin 2) gravitational
Adenauer G. Casali, Bin Wang, Bin Wang, Bin Wang, Bin Wang, Bin Wang, C. Csáki, C. Csáki, C. Lanczos, C. Lanczos, D.J. Chung, D.J. Chung, D.S. Goldwirth, David Langlois, Dmitry S. Gorbunov, E. Abdalla, E. Abdalla, E. Witten, Elcio Abdalla, F. Quevedo, G. Darmois, G.F. Giudice, H. Ishihara, Hideo Kodama, K. Koyama, K. Koyama, L. Randall, L. Randall, M. Gasperini, N. Deruelle, P. Binetruy, P. Horava, R. Caldwell, R. Easther, Roy Maartens, Shin’ichi Nojiri, Shin’ichi Nojiri, T. Hiramatsu, W. Israel, W. Israel   +39 more
core   +1 more source

Cosmological perturbations in generalised dark Lagrangians

Journal of High Energy Physics, 2018
We describe a new method to parameterise dark energy theories including massive gravity, elastic dark energy and tensor-metric theories. We first examine the existing framework which describes any second order Lagrangian which depends on the variation of
James Edholm, Jonathan Pearson
doaj   +1 more source

Non-linear stability of α′-corrected Friedmann equations

Journal of High Energy Physics, 2023
We study the non-linear stability of fixed-point solutions to the α′-exact equations from O(d, d) invariant cosmology, with and without matter perturbations.
Heliudson Bernardo, Jan Chojnacki, Vincent Comeau   +2 more
doaj   +1 more source

Scalar perturbations in cosmological f(R) models: the cosmic screening approach

European Physical Journal C: Particles and Fields, 2018
We investigate cosmological perturbations for nonlinear f(R) models within the cosmic screening approach. Matter is considered both in the form of a set of discrete point-like massive bodies and in the form of a continuous pressureless perfect fluid.
Özgür Akarsu, Ruslan Brilenkov, Maxim Eingorn, Valerii Shulga, Alexander Zhuk   +4 more
doaj   +1 more source

Magnetized cosmological perturbations [PDF]

, 2000
A large-scale cosmic magnetic field affects not only the growth of density perturbations, but also rotational instabilities and anisotropic deformation in the density distribution.
A. Davis, A. Davis, A. Kosowsky, A.D. Challinor, A.D. Dolgov, A.M. Wolfe, B. Ratra, C.G. Tsagas, C.G. Tsagas, Christos G. Tsagas, D. Grasso, D.D. Harari, D.T. Son, E. Battaner, E. Kim, E.A. Calzetta, E.R. Harrison, E.S. Scannapieco, G.F.R. Ellis, G.F.R. Ellis, G.F.R. Ellis, H. Kodama, I. Wasserman, J. Adams, J.D. Barrow, J.D. Barrow, K. Enqvist, K. Jedamzik, K. Subramanian, K. Subramanian, M. Abramowitz, M. Bruni, M. Gasperini, M.S. Turner, P.P. Kronberg, P.P. Kronberg, R. Durrer, R. Maartens, R. Maartens, R. Maartens, R. Maartens, R. Maartens, R.M. Kulsrud, Roy Maartens, S.W. Hawking, T. Padmanabhan, T. Vachaspati, T.V. Ruzmaikina, V.F. Mukhanov, Ya. B. Zeldovich   +49 more
core   +2 more sources

Dependence of Inflationary Reconstruction upon Cosmological Parameters

, 1995
The inflationary potential and its derivatives determine the spectrum of scalar and tensor metric perturbations that arise from quantum fluctuations during inflation.
A. A. Starobinskii, A. A. Starobinskii, A. G. Doroshkevich, A. G. Doroshkevich, A. H. Guth, A. Kosowsky, A. R. Liddle, A. R. Liddle, A. R. Liddle, A. R. Liddle, D. H. Lyth, E. J. Copeland, E. J. Copeland, E. J. Copeland, E. J. Copeland, E. J. Copeland, F. Lucchin, G. Efstathiou, G. Efstathiou, J. M. Bardeen, J. P. Ostriker, J. Silk, J. Silk, L. F. Abbott, L. F. Abbott, L. Knox, L. Knox, L. Kofman, L. Krauss, M. Kamionkowski, M. S. Turner, M. S. Turner, M. S. Turner, M. S. Turner, M. S. Turner, M. S. Turner, M. S. Turner, M. White, M. White, Martin White, Michael S. Turner, N. Sugiyama, P. J. E. Peebles, P. J. E. Peebles, P. J. E. Peebles, R. Fabbri, R. K. Sachs, S. M. Carroll, S. W. Hawking, V. A. Rubakov   +49 more
core   +1 more source