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Effects of the interaction between dark energy and dark matter on cosmological parameters

Jian-Hua He, Bin Wang

TL;DR

The paper addresses whether phenomenological interactions between dark energy and dark matter can ease the cosmic coincidence problem. It tests five coupling forms across two time-varying DE EoS parameterizations, plus a constant EoS, using SN Ia, BAO, and CMB shift data with MCMC. The results indicate that, for a time-varying EoS ω_I, the product coupling Q ∝ ρ_DE ρ_DM most effectively alleviates the coincidence problem and avoids unphysical densities, while other couplings often fail or introduce pathologies; for ω_II, only the product coupling yields meaningful alleviation, and for constant ω none of the couplings succeeds. The findings highlight a strong dependence on the DE EoS and suggest extending the analysis to more general parameterizations and larger data sets to robustly constrain DE–DM interactions.

Abstract

We examine the effects of possible phenomenological interactions between dark energy and dark matter on cosmological parameters and their efficiency in solving the coincidence problem. We work with two simple parameterizations of the dynamical dark energy equation of state and the constant dark energy equation of state. Using observational data coming from the new 182 Gold type Ia supernova samples, the shift parameter of the Cosmic Microwave Background given by the three-year Wilkinson Microwave Anisotropy Probe observations, and the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey, we perform a statistical joint analysis of different forms of phenomenological interactions between dark energy and dark matter.

Effects of the interaction between dark energy and dark matter on cosmological parameters

TL;DR

The paper addresses whether phenomenological interactions between dark energy and dark matter can ease the cosmic coincidence problem. It tests five coupling forms across two time-varying DE EoS parameterizations, plus a constant EoS, using SN Ia, BAO, and CMB shift data with MCMC. The results indicate that, for a time-varying EoS ω_I, the product coupling Q ∝ ρ_DE ρ_DM most effectively alleviates the coincidence problem and avoids unphysical densities, while other couplings often fail or introduce pathologies; for ω_II, only the product coupling yields meaningful alleviation, and for constant ω none of the couplings succeeds. The findings highlight a strong dependence on the DE EoS and suggest extending the analysis to more general parameterizations and larger data sets to robustly constrain DE–DM interactions.

Abstract

We examine the effects of possible phenomenological interactions between dark energy and dark matter on cosmological parameters and their efficiency in solving the coincidence problem. We work with two simple parameterizations of the dynamical dark energy equation of state and the constant dark energy equation of state. Using observational data coming from the new 182 Gold type Ia supernova samples, the shift parameter of the Cosmic Microwave Background given by the three-year Wilkinson Microwave Anisotropy Probe observations, and the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey, we perform a statistical joint analysis of different forms of phenomenological interactions between dark energy and dark matter.

Paper Structure

This paper contains 14 sections, 22 equations, 11 figures.

Table of Contents

  1. Introduction
  2. Phenomenological models describing the interaction between DE and DM
  3. The coupling is proportional to the energy density of DE
  4. The coupling is proportional to the energy density of DM
  5. The coupling is proportional to the total energy density of DE and DM
  6. The coupling is proportional to the linear combination of energy densities of DE and DM
  7. The coupling is proportional to the product of energy densities of DE and DM
  8. Observational constraints
  9. The coupling is proportional to the energy density of DE
  10. The coupling is proportional to the energy density of DM
  11. The coupling is proportional to the total energy density of DE and DM
  12. The coupling is proportional to the linear combination of energy densities of DE and DM
  13. The coupling is proportional to the product of energy densities of DE and DM
  14. conclusions and discussions

Figures (11)

  • Figure 1: The likelihood for coupling parameters when the interaction is chosen as $\delta H\rho_{DE}$
  • Figure 2: These figures show clearly the behaviors of different dark sectors during the late time evolution of universe with best-fitted data for coupling $\delta H\rho_{DE}$. The red dotted line denotes the noninteracting case.The left one corresponds to EoS $\omega_I$,the middle one is EoS $\omega_{II}$ and the right one is constant EoS
  • Figure 3: The likelihood for coupling parameters when the interaction is chosen as $\delta H\rho_{DM}$.
  • Figure 4: These figures show clearly the behaviors of different dark sectors during the late time evolution of universe with best-fitted data for the coupling $\delta H\rho_{DM}$. The red dotted line denotes the noninteracting data.The left one corresponds to EoS $\omega_I$,the middle one is EoS $\omega_{II}$ and the right one is constant EoS
  • Figure 5: The likelihood for coupling parameters when the interaction is chosen as $\delta H(\rho_{DM}+\rho_{DE})$.
  • ...and 6 more figures