New tests of dark sector interactions from the full-shape galaxy power spectrum

Abstract

We explore the role of redshift-space galaxy clustering data in constraining nongravitational interactions between dark energy (DE) and dark matter (DM), for which state-of-the-art limits have so far been obtained from late-time background measurements. We use the joint likelihood for prereconstruction full-shape (FS) galaxy power spectrum and postreconstruction Baryon Acoustic Oscillation (BAO) measurements from the BOSS DR12 sample, alongside Cosmic Microwave Back ground (CMB) data from Planck: from this dataset combination we infer H0 ¼ 68.02þ0.49 −0.60 km=s=Mpc and the 2σ lower limit ξ > −0.12, among the strongest limits ever reported on the DM-DE coupling strength ξ for the particular model considered. Contrary to what has been observed for the ΛCDM model and simple extensions thereof, we find that the CMB þ FS combination returns tighter constraints compared to the CMB þ BAO one, suggesting that there is valuable additional information contained in the broadband of the power spectrum. We test this finding by running additional CMB-free analyses and removing sound horizon information, and discuss the important role of the equality scale in setting constraints on DM-DE interactions. Our results reinforce the critical role played by redshift-space galaxy clustering measurements in the epoch of precision cosmology, particularly in relation to tests of nonminimal dark sector extensions of the ΛCDM model.