New constraints on interacting dark energy from DESI DR2 BAO observations

In its second data release (DR2), the Dark Energy Spectroscopic Instrument (DESI) publicly released measurements of Baryon Acoustic Oscillations (BAO) from over 13.1 million galaxies and 1.6 million quasars, covering the redshift range 0.295 ≤ z ≤ 2.330. In this work, we investigate the impact of this new dataset on dark sector interaction models, which are motivated by nongravitational interactions between dark energy (DE) and dark matter (DM), commonly referred to as interacting dark energy models (IDE). We focus on two frameworks: the traditional IDE model and the recently proposed sign-switching Interacting model (S-IDE), aiming to derive new and robust constraints on both scenarios. After carefully selecting the sample for the joint analysis, ensuring compatibility among the data without significant tension, our main results indicate that both models can alleviate the H0 tension, reducing it to moderate tension approximately 2.7σ. The IDE model shows compatibility with the latest S8 constraints from cosmic shear surveys, while the S-IDE model predicts lower values of S8, which align with alternative perspectives on the S8 tension. For the traditional IDE model, we derive new bounds for the coupling parameter, marking the strongest constraints to date through geometric measurements. This highlights the crucial role that supernova samples can play in refining these constraints. For the S-IDE model, we find mild evidence (over 2σ) for a non-zero coupling, once the PantheonPlus dataset calibrated with Cepheid-based magnitude measurements is included in the analysis.