Speaker
Description
Recent cosmological data from DESI motivate modelling of extensions to the standard model that modifies late-time phenomenology, while maintaining concordance with early Universe, local laboratory and solar system experiments. One promising way to do so is to have additional cosmologically relevant degrees of freedom that are negligible until they are activated in underdensities of the late-time Universe by a phase transition governed by the ambient matter density. The interplay with nonlinearities in late-time matter structures provides new signatures, such as environment-dependent clustering. Finding predictions requires numerical simulations. I will present results on the matter 1-point function, gravitational wave emission and some future directions.