2021/02/10 by Genly León, Esteban González, Leon, Genly +7
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Mathematical Physics (math-ph) #Solar and Space Plasma Dynamics
paper · pdf · doi:10.48550/arxiv.2102.05551
openalex publication_date 2021/02/10 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
Scalar field cosmologies with a generalized harmonic potential and matter\nwith energy density \ρm, pressure pm, and barotropic equation of state\n(EoS) pm=(\γ-1)\ρm, ; \γ\∈[0,2] in Kantowski-Sachs (KS) and\nclosed Friedmann--Lema itre--Robertson--Walker (FLRW) metrics are\ninvestigated. We use methods from non--linear dynamical systems theory and\naveraging theory considering a time--dependent perturbation function D. We\ndefine a regular dynamical system over a compact phase space, obtaining global\nresults. That is, for KS metric the global late--time attractors of full and\ntime--averaged systems are two anisotropic contracting solutions, which are\nnon--flat locally rotationally symmetric (LRS) Kasner and Taub (flat LRS\nKasner) for 0\≤ \γ \≤ 2, and flat FLRW matter--dominated universe if\n0\≤ \γ \≤ \(2)/(3). For closed FLRW metric late--time attractors\nof full and averaged systems are a flat matter--dominated FLRW universe for\n0\≤ \γ \≤ \(2)/(3) as in KS and Einstein-de Sitter solution for\n0\≤\γ<1. Therefore, time--averaged system determines future asymptotics\nof full system. Also, oscillations entering the system through Klein-Gordon\n(KG) equation can be controlled and smoothed out when D goes monotonically to\nzero, and incidentally for the whole D-range for KS and for closed FLRW (if\n0\≤ \γ< 1) too. However, for \γ\≥ 1 closed FLRW solutions of\nthe full system depart from the solutions of the averaged system as D is\nlarge. Our results are supported by numerical simulations.\n