Observational constraints on dark matter-dark energy scattering cross section

TL;DR

This study constrains a momentum-exchange (elastic) DM–DE scattering model using Planck2015 CMB data, BAO measurements, and CFHTLenS weak lensing. The interaction is encoded in a drag term with $\xi = \sigma_d / m_{\rm dm}$, affecting only perturbations and leaving the background expansion unchanged. Through MCMC analyses with CLASS/Monte Python, the authors find tight upper bounds $\xi \lesssim \mathcal{O}(10^{-4})$, translating to $\sigma_d < 10^{-29}\ \text{cm}^2\, ( m_{\rm dm} c^2 / \text{GeV} )$ for typical DM masses, implying a very weak DM–DE coupling. The results indicate negligible impact on background cosmology but potential effects on structure growth, guiding future N-body simulations and generalizations to energy exchange scenarios. These constraints provide a benchmark for DM–DE interaction models and reinforce the standard $\Lambda$CDM paradigm at the background level while allowing precise perturbative limits.

Abstract

In this letter, we report precise and robust observational constraints on dark matter-dark energy scattering cross section, using the latest data from cosmic microwave background (CMB) Planck temperature and polarization, baryon acoustic oscillations (BAO) measurements and weak gravitational lensing data from Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). The scattering scenario consists of a pure momentum exchange between the dark components, and we find $σ_d < 10^{-29} \, {\rm cm^2}$ at 95\% CL from the joint analysis (CMB + BAO + CFHTLenS), for typical dark matter particle mass of the order 1-10 ${\rm GeV}/c^2$. We notice that the scattering among the dark components may influence the growth of large scale structure in the Universe, leaving the background cosmology unaltered.

Figures (4)

• Figure 1: One-dimensional marginalized probability distribution of $\xi$
• Figure 2: One-dimensional marginalized distribution, two-dimensional 1$\sigma$ and 2$\sigma$ confidence contours for some selected parameters.
• Figure 3: Relative deviation of CMB TT power spectrum from the base line Planck 2015 $\Lambda$CDM model (red line) for various values of $\xi$ while the other parameters are fixed to their bestfit mean values as given in Table \ref{['tab1']}.
• Figure 4: Relative deviation of matter power spectrum from the base line Planck 2015 $\Lambda$CDM model (red line) for various values of $\xi$ while the other parameters are fixed to their bestfit mean values as given in Table \ref{['tab1']}.