HEP-Astro Seminar | Interacting Dark Energy

The ultimate nature of dark matter and dark energy are fundamental questions in cosmology; these two sectors may well interact with each other and observational bounds allow interesting possibilities. Indeed, some interactions may help to resolve some observed tensions between high and low redshift probes of structure. I will discuss a class of models where the interactions take the form of pure momentum exchange and show how these can lead to a dark energy sound speed that deviates from unity.