The non-linear evolution of plasma waves in a magnetar magnetosphere

Magnetars are neutron stars characterized by a strong and actively evolving magnetic field responsible for powering a variety of transients. The dynamic evolution of the magnetic field will naturally perturb the magnetosphere launching plasma waves. This highly magnetized environment effectively admits only two low frequency wave modes: the Alfvén wave and the fast magnetosonic (fast) wave. In this talk, I will discuss the evolution of both of these wave modes. I will show that even if fast waves are not directly injected into the magnetosphere, Alfvén waves will spontaneously convert into energetic fast waves, making them an inevitable consequence of a dynamic magnetar magnetosphere. This is particularly important because fast waves in this environment will steepen into a type of shock purported to be the strongest in the universe. I will conclude by presenting results of 2D simulations of these “monster shocks” and discussing their potential connection to Fast Radio Bursts.