Speaker: Claudio Llinares, UiO, Faculty of Mathematics and Natural Sciences, Institute of Theoretical Astrophysics, Oslo

In the context of scalar tensor theories for gravity, there is a universally adopted hypothesis when running N-body simulations that time derivatives in the equation of motion for the scalar field are negligible. While the approximation greatly simplifies the simulation techniques, its validity is still a matter of debate.  I will present a method that can be used to simulate scalar fields beyond the static approximation as well as results coming from non-static cosmological simulations in the context of the symmetron models.  These non-static symmetron simulations show in particular that the model can lead to the formation of domain walls.  I will conclude by reviewing our latest results on the properties of these particular topological defects.