Revisit of the interacting holographic dark energy model after Planck 2015

TL;DR

This paper tests five phenomenological IHDE models, each with a distinct form of the dark-energy–dark-matter coupling $Q$, against a joint dataset comprising JLA SN Ia, Planck 2015 CMB distance priors, BAO, and a local $H_0$ measurement. By solving the IHDE background evolution with the holographic density $\rho_{\rm de}=3c^2M_{\rm pl}^2L^{-2}$ (with $L$ the future event horizon) and comparing models via $\mathrm{AIC}$ and $\mathrm{BIC}$, the authors find that IHDE5 ($Q_5=3\beta H\frac{\rho_{\rm de}\rho_{\rm c}}{\rho_{ m de}+\rho_{ m c}}$) provides the best fit among IHDEs, while IHDE2 ($Q_2=3\beta H\rho_{\rm c}$) is the least favored. The analysis detects $\beta>0$ at roughly $2\sigma$ significance for IHDE1 and IHDE5, implying dark energy decays into dark matter and correlates with a larger $c$, which reduces the phantom big-rip risk. The study highlights the potential preference for a holographic dark-energy model with inter-dark-sector coupling but cautions that perturbations were not included, suggesting future work with a PPF framework to fully exploit the data.

Abstract

We investigate the observational constraints on the interacting holographic dark energy model. We consider five typical interacting models with the interaction terms $Q=3βHρ_{\rm{de}}$, $Q=3βHρ_{\rm{c}}$, $Q=3βH(ρ_{\rm{de}}+ρ_{\rm c})$, $Q=3βH\sqrt{ρ_{\rm{de}}ρ_{\rm c}}$, and $Q=3βH\frac{ρ_{\rm{de}}ρ_{c}}{ρ_{\rm{de}}+ρ_{\rm c}}$, respectively, where $β$ is a dimensionless coupling constant. The observational data we use in this paper include the JLA compilation of type Ia supernovae data, the Planck 2015 distance priors data of cosmic microwave background observation, the baryon acoustic oscillations measurements, and the Hubble constant direct measurement. We make a comparison for these five interacting holographic dark energy models by employing the information criteria, and we find that, within the framework of holographic dark energy, the $Q=3βH\frac{ρ_{\rm{de}}ρ_{\rm c}}{ρ_{\rm{ de}}+ρ_{\rm c}}$ model is most favored by current data, and the $Q=3βHρ_{\rm c}$ model is relatively not favored by current data. For the $Q=3βHρ_{\rm{de}}$ and $Q=3βH\frac{ρ_{\rm{de}}ρ_{\rm c}}{ρ_{\rm{ de}}+ρ_{\rm c}}$ models, a positive coupling $β$ can be detected at more than 2$σ$ significance.

Figures (6)

• Figure 1: Graphical representation of the results of $\Delta$AIC and $\Delta$BIC for the HDE model and the IHDE models.
• Figure 2: The SN+CMB+BAO+$H_0$ constraints on the HDE model and the IHDE models. The 68.3% and 95.4% confidence level contours are shown in the $\Omega_{\rm{m0}}$--$c$ plane.
• Figure 3: The SN+CMB+BAO+$H_0$ constraints on the HDE model and the IHDE models. The 68.3% and 95.4% confidence level contours are shown in the $\Omega_{\rm{m0}}$--$\beta$ plane. The red dashed line denotes the case of $\beta=0$.
• Figure 4: The SN+CMB+BAO+$H_0$ constraints on the IHDE models. The 68.3% and 95.4% confidence level contours are shown in the $c$--$\beta$ plane. The red dashed line denotes the case of $\beta=0$.
• Figure 5: One-dimensional marginalized posterior distributions of parameters $\beta$ (left panel) and $c$ (right panel) for the HDE model and the IHDE models, from the SN+CMB+BAO+$H_0$ data. The dark yellow dashed lines denote the cases of $\beta=0$ (left panel) and $c=1$ (right panel).