Repeating fast radio bursts caused by small bodies orbiting a pulsar or a magnetar

Understand

Asteroids orbiting into the highly magnetized and highly relativistic wind of a pulsar offer a favourable configuration for repeating fast radio bursts (FRB).

• The body in direct contact with the wind develops a trail formed of a stationary Alfv\'en wave, called an \textit{Alfv\'en wing}.
• When an element of wind crosses the Alfv\'en wing, it sees a rotation of the ambient magnetic field that can cause radio-wave instabilities.
• In the observer's reference frame, the waves are collimated in a very narrow range of directions, and they have an extremely high intensity.