RT Journal Article
T1 Cosmological perturbations in coherent oscillating scalar field models
A1 Ruiz Cembranos, José Alberto
A1 López Maroto, Antonio
A1 Nuñez Jareño, Santos José
AB The fact that fast oscillating homogeneous scalar fields behave as perfect fluids in average and their intrinsic isotropy have made these models very fruitful in cosmology. In this work we will analyse the perturbations dynamics in these theories assuming general power law potentials V(ϕ) = λ|ϕ|^n /n. At leading order in the wavenumber expansion, a simple expression for the effective sound speed of perturbations is obtained c_eff^ 2  = ω = (n − 2)/(n + 2) with ω the effective equation of state. We also obtain the first order correction in k^ 2/ω_eff^ 2 , when the wavenumber k of the perturbations is much smaller than the background oscillation frequency, ω_eff. For the standard massive case we have also analysed general anharmonic contributions to the effective sound speed. These results are reached through a perturbed version of the generalized virial theorem and also studying the exact system both in the super-Hubble limit, deriving the natural ansatz for δϕ; and for sub-Hubble modes, exploiting Floquet’s theorem.
PB Springer
SN 1029-8479
YR 2016
FD 2016-03-03
LK https://hdl.handle.net/20.500.14352/24513
UL https://hdl.handle.net/20.500.14352/24513
LA eng
NO Open Access, © The Authors.© Springer Verlag, A. G.Article funded by SCOAP3.This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.This work has been supported by MICINN (Spain) project numbers FIS2011-23000, FPA2011-27853-01, FIS2014-52837-P and Consolider-Ingenio MULTIDARK CSD2009- 00064. S.J.N.J. acknowledge support from Complutense University under grant CT4/14. We would like to thank Alberto Díez Tejedor for his useful comments.
NO Ministerio de Ciencia e Innovación (MICINN), España
NO Proyecto Método de Multimensajeros para la Detección de la Materia Oscura (MultiDark), CONSOLIDER-INGENIO
NO Ministerio de Economía y Competitividad (MINECO), España
NO Actividad Investigadora CONSOLIDER - INGENIO 2010 (MINECO)
NO Universidad Complutense de Madrid (UCM)
NO Sponsoring Consortium for Open Access Publishing in Particle Physics (SCOAP3)
DS Docta Complutense
RD 10 abr 2025