Astrophysics

I will discuss the cosmology of galileon models with a Minkowski limit and discuss whether they can account for the currently observed cosmological model. The full galileon model predicts the speed of gravitational waves to be different from that of photons. I will discuss this and compare with observations. I will then discuss a subdominant galileon model which is compatible. Finally I will discuss the shape dependence of screening in galileon models, showing that the fifth force is unscreened for planar objects.

I will discuss phenomena associated with particle production and field excitation during inflation. In the first part of the talk I will present several
signatures that can originate from the coupling of an axion inflaton to gauge fields. In the second part I will test the robustness of the standard
implications associated with the detection of a gravity wave (GW) signal at CMB scales, by discussing what conditions can allow a visible
sourced GW background that exceeds the vacuum one (without simultaneously overproduce scalar perturbations), and by providing a concrete
example. In the final part I will review the phenomenology of trapped inflation, which is an interesting and minimal mechanism where particle production
provides the main friction for the motion of the inflaton.