Compression fronts from fast radio bursts

Abstract

When a fast radio burst (FRB) expands from its source through a surrounding tenuous plasma, it strongly heats and compresses the plasma at radii up to $\sim 10^{14}$cm. The likely central engines of FRBs are magnetars, and their ambient plasma at radii $r\gg 10^{10}$cm is a magnetized $e^\pm$ wind. We formulate basic equations of the FRB-plasma interaction, solve them numerically, and describe the physical picture of the interaction. We find the following: (1) FRBs emitted at $r<r_{\rm stoch}\sim 10^{12}$cm induce fast stochastic heating and strong compression of the wind, sweeping it like a broom. The outcome of this interaction is determined by the energy losses of the radio wave; we evaluate the parameter space where FRBs survive and escape. (2) At radii $r>r_{\rm stoch}$, FRB induces regular particle oscillations in the radio wave with the standard strength parameter $a$, and drives a compression wave in the wind. At $r>r_\star\sim 10^{13}$cm, the compression wave becomes locally quasisteady, with compression factor $1+a^2$. FRBs avoid damping if they are released into the wind medium outside $r_{\rm damp}\sim 10^{11}$cm.