New constraints on interacting dark energy from cosmic chronometers

TL;DR

The paper investigates whether a direct interaction between dark energy and dark matter is present by introducing a general coupling parameter delta in a FRW framework and constraining it with cosmic chronometers, a local H0 measurement, SNe Ia (JLA), BAO, and Planck 2015 CMB distance priors. Using CLASS+MontePython, the study shows that CC+H0 data alone prefer a nonzero delta and a phantom-style EOS (w<-1), while the full data combination drives delta toward zero but still prefers w<-1 at 3σ. These results indicate a mild, not decisive, preference for IDE and demonstrate the utility of cosmic chronometer data in breaking degeneracies among late-time cosmological parameters. The inferred H0 and matter density ranges are consistent with a concordance-like expansion history, albeit with room for a small DM-DE coupling in the late universe.

Abstract

We use the latest compilation of observational Hubble parameter measurements estimated with the differential evolution of cosmic chronometers, in combination with the local value of the Hubble constant recently measured with 2.4% precision, to constrain the cosmological scenario where dark energy interacts directly with the dark matter sector. To diminish the degeneracy between the parameters we additionally consider standard probes, such as Supernovae Type Ia from joint light curves (JLA) sample, Baryon Acoustic Oscillation distance measurements (BAO), and cosmic microwave background data from Planck 2015 estimations. Our analysis shows that the direct interaction between dark energy and dark matter is mildly flavored, while the dark energy equation-of-state parameter is w < - 1 at 3$σ$ confidence level.

Figures (4)

• Figure 1: The CMB TT power spectrum $D^{TT}_l =l(l+ 1)C_l/2 \pi\mu K^2$, for the interacting scenario at hand (dashed-red line) and for the flat $\Lambda$CDM cosmology (black-solid line). The data with their error bars have been taken from Planck Collaboration data_cmb.
• Figure 2: The theoretical prediction for linear matter power spectrum, for the interacting scenario at hand (dashed-red line) and for the flat $\Lambda$CDM cosmology (black-solid line).
• Figure 3: 68.3$\%$ and 95.4$\%$ confidence-level contour plots for the free parameters of the scenario of interacting dark energy, using only $CC$ + $H_0$ observational data. Additionally, we depict the marginalized one-dimensional posterior distribution, where the dashed curve stands for the average likelihood distribution.
• Figure 4: 68.3$\%$ and 95.4$\%$ confidence-level contour plots for the free parameters of the scenario of interacting dark energy, using $CC$ + $H_0$ + SNeIa/JLA + BAO + CMB observational data. Additionally, we depict the marginalized one-dimensional posterior distribution, where the dashed curve stands for the average likelihood distribution.