Cosmological status of Lagrangian theory of density perturbations

Abstract

We show that hydrodynamical and field approaches in theory of cosmological scalar perturbations are equivalent for a single medium. We also give relations between notations introduced by V. Lukash, J. Bardeen, J. Bardeen et al. and G. Chibisov and V. Mukhanov.Comment: 8 pages, no figures, submitted to Astronomy Report

Probing large-scale magnetism with the cosmic microwave background

“…When δp nad → 0, Π tot → 0 and in the absence of electromagnetic contributions, Eq. (3.53) coincides with the evolution equation of the normal mode of a relativistic irrotational fluid derived by Lukash [73,74,75]. Equation (3.53) must be supplemented by the evolution equation for the anisotropic stress.…”

“…The variable of Eqs. (2.44) and (2.46) has been first discussed by Lukash [73] (see also [74,75]) when analyzing the quantum excitations of an irrotational and relativistic fluid. The canonical normal mode identified in Ref.…”

Fluctuations of inflationary magnetogenesis

“…The variables of Eq. (5.34) are the scalar field analog of the quantum excitations of an irrotational and relativistic fluid firstly discussed by Lukash [37] (see also [38,39,40]) right after one of the first formulations of inflationary dynamics [41]. The canonical normal mode identified in Ref.…”

“…In concluding this section it is appropriate to remark that Eqs. [37] (see also [38,39,40]) right after one of the first formulations of inflationary dynamics [41]. The canonical normal mode identified in Ref.…”

“…where z t = (a 2 √ p t + ρ t )/(Hc st ). The variable z t R is, up to a sign, the normal mode of an irrotational and relativistic fluid discussed by Lukash [37] (see also [38,39]) with the difference of the source term containing the dependence on the gauge inhomogeneities. Both Eqs.…”