Large-scale stable interacting dark energy model: Cosmological perturbations and observational constraints

Abstract

Dark energy might interact with cold dark matter in a direct, nongravitational way. However, the usual interacting dark energy models (with constant w) suffer from some catastrophic difficulties. For example, the Q ∝ ρc model leads to an early-time large-scale instability, and the Q ∝ ρ de model gives rise to the future unphysical result for cold dark matter density (in the case of a positive coupling). In order to overcome these fatal flaws, we propose in this paper an interacting dark energy model (with constant w) in which the interaction term is carefully designed to realize that Q ∝ ρ de at the early times and Q ∝ ρc in the future, simultaneously solving the early-time superhorizon instability and future unphysical ρc problems. The concrete form of the interaction term in this model is Q = 3βH, where β is the dimensionless coupling constant. We show that this model is actually equivalent to the decomposed new generalized Chaplygin gas (NGCG) model, with the relation β = −αw. We calculate the cosmological perturbations in this model in a gauge-invariant way and show that the cosmological perturbations are stable during the whole expansion history provided that β > 0. Furthermore, we use the Planck data in conjunction with other astrophysical data to place stringent constraints on this model (with eight parameters), and we find that indeed β > 0 is supported by the joint constraint at more than 1σ level. The excellent theoretical features and the support from observations all indicate that the decomposed NGCG model deserves more attention and further investigation.PACS numbers: 95.36.+x, 98.80.Es,

Observational constraints on sign-changeable interaction models and alleviation of the H0 tension

“…x /(ρ c + ρ x ), nonlinear forms, etc [25,32,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85].…”

Reexploration of interacting holographic dark energy model: cases of interaction term excluding the Hubble parameter

“…where Q is the phenomenological interaction term [113][114][115][116][117][118][119][120][121][122], denoting the energy transfer rate between dark energy and dark matter. In this paper, we consider the following five cases in the IHDE model:…”

A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure

“…For all models, the present-day fractional density parameters of CDM, baryons, and radiation are fixed to be: Ω c0 = 0.23, Ω b0 = 0.04, and Ω r0 = 2.469 × 10 −5 h −2 (1 + 0.2271N eff ) (with the Hubble constant h = 0.7 and the effective number of neutrino species N eff = 3.046). For properly choosing the values of EoS and coupling, we refer to the literature [65][66][67][68]. We will first test the impact of w in the IwCDM models.…”