Speaker
Description
Interactions between dark matter and dark energy have been explored in a variety of contexts, with recent motivations coming from the ongoing cosmological tensions. However, many nonminimally coupled models are either strongly constrained by background observations or are phenomenological in nature. In this talk, I will present a new class of interacting Lagrangian models where scalar fields couple to the intrinsic entropy of matter. These couplings share similarities with the âpure-momentum transferâ models, modifying only the Euler equation at linear order. The new degrees of freedom associated with intrinsic entropy perturbations play a crucial role in suppressing or enhancing the matter power spectrum on small scales, while leaving key features of the CMB unchanged. Alongside their observational signatures, I will discuss the physical interpretation of these models in terms of non-equilibrium thermodynamics and the relation to non-adiabatic fluid models.
