Can a Strong Radio Burst Escape the Magnetosphere of a Magnetar

We examine the possibility that fast radio bursts (FRBs) are emitted inside the magnetosphere of a magnetar. On its way out, the radio wave must interact with a low-density $e^\pm$ plasma in the outer magnetosphere at radii $10^9$-$10^{10}\,$cm. In this region, the magnetospheric particles have a huge cross section for scattering the wave. As a result, the wave strongly interacts with the magnetosphere and compresses it, depositing the FRB energy into the compressed field and the scattered radiation. The scattered spectrum extends to the $\gamma$-ray band and triggers $e^\pm$ avalanche, further boosting the opacity. These processes choke FRBs, excluding emission of observed bursts from radii $R\ll 10^{10}\,$cm.