Constraints on the Engines of Fast Radio Bursts

Understand

We model the sample of fast radio bursts (FRB), including the newly discovered CHIME repeaters, using the synchrotron blast wave model of Metzger, Margalit & Sironi (2019).

• This model postulates that FRBs are precursor radiation from ultra-relativistic magnetized shocks generated as flare ejecta from a central engine collide with an effectively stationary external medium.
• Downward drifting of the burst frequency structure naturally arises from deceleration of the blast-wave.
• The data are consistent with FRBs being produced by flares of energy $E_{\rm flare} \sim 10^{43}-10^{46}(f_{\xi}/10^{-3})^{-4/5}$ erg, where $f_{\xi}$ is the maser efficiency, and minimum bulk Lorentz factors $\Gamma \approx 10^2-10^3$, which generate the observed FRBs at shock radii $r_{\rm sh} \sim 10^{12}-10^{13}$ cm.