Results 31 to 40 of about 967 (212)
COSMOLOGICAL PERTURBATIONS IN PRESENCE OF SCALAR FIELDS
Odessa Astronomical Publications, 2014 We investigate the role of the scalar field assuming its presence at late stages of the Universe evolution together with dust presented by a system of an arbitrary number of gravitating masses (galaxies, groups of galaxies and clusters of galaxies) and ...
A. Yu. Burgazli, M. Eingorn, A. Zhuk
doaj +1 more source
Cosmological perturbations engendered by discrete relativistic species
European Physical Journal C: Particles and Fields, 2023 Within the extension of the $$\varLambda $$ Λ CDM model, allowing for the presence of neutrinos or warm dark matter, we develop the analytical cosmological perturbation theory.
Maksym Brilenkov +2 more
doaj +1 more source
PERTURBATIONS IN BOUNCING COSMOLOGICAL MODELS [PDF]
International Journal of Modern Physics D, 2004 I describe the features and general properties of bouncing models and the evolution of cosmological perturbations on such backgrounds. I will outline possible observational consequences of the existence of a bounce in the primordial Universe and I will make a comparison of these models with standard long inflationary scenarios.
openaire +3 more sources
Quantum Gravity and Cosmological Density Perturbations
Galaxies, 2014 We explore the possible cosmological consequences of a running Newton’s constant, G(⎕), as suggested by the non-trivial ultraviolet fixed point scenario for Einstein gravity with a cosmological constant term.
Herbert W. Hamber, Reiko Toriumi
doaj +1 more source
Black hole perturbation theory and multiple polylogarithms
Journal of High Energy Physics, 2023 We study black hole linear perturbation theory in a four-dimensional Schwarzschild (anti) de Sitter background. When dealing with a positive cosmological constant, the corresponding spectral problem is solved systematically via the Nekrasov-Shatashvili ...
Gleb Aminov +4 more
doaj +1 more source
ASYMPTOTICS OF LINEARIZED COSMOLOGICAL PERTURBATIONS [PDF]
Journal of Hyperbolic Differential Equations, 2010 In cosmology an important role is played by homogeneous and isotropic solutions of the Einstein–Euler equations and linearized perturbations of these. This paper proves results on the asymptotic behavior of scalar perturbations both in the approach to the initial singularity of the background model and at late times. The main equation of interest is a
Allen, P., Rendall, A.
openaire +3 more sources
Semiclassicality and decoherence of cosmological perturbations [PDF]
Classical and Quantum Gravity, 1996 Revised version to appear in Class. Quantum Grav. All prior conclusions hold.
Polarski, David, Starobinsky, Alexei A.
openaire +3 more sources
Cosmological perturbations on the phantom brane [PDF]
Journal of Cosmology and Astroparticle Physics, 2016 We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, $w_{\rm eff} < -1$, but no big-rip future singularity. In addition to matter and radiation, the braneworld possesses a new effective degree of freedom - the 'Weyl fluid' or 'dark ...
Bag, Satadru +3 more
openaire +2 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
Theory of cosmological perturbations with cuscuton [PDF]
Journal of Cosmology and Astroparticle Physics, 2017 This paper presents the first derivation of the quadratic action for curvature perturbations, $ζ$, within the framework of cuscuton gravity. We study the scalar cosmological perturbations sourced by a canonical single scalar field in the presence of cuscuton field.
Boruah, Supranta S. +2 more
openaire +3 more sources