Self-trapping as the possible beaming mechanism for FRBs

Abstract

Enigmatic fast radio bursts (FRBs), still eluding a rational explanation, are astronomical millisecond-scale radio flashes. They are thought to be of an extragalactic origin, with luminosities orders of magnitude larger than any known short time-scale radio transients. Numerous models have been proposed in order to explain these powerful bursts but none of them is commonly accepted; it is not clear which of these scenarios might account for real FRBs. The crucial question remains: what makes FRBs so exceptionally powerful and rare? If the bursts are related to something happening with a star-scale object and its immediate neighbourhood, why do all detected FRB events take place in very distant galaxies and never in our own Galaxy? In this paper we argue that a non-linear phenomenon – self-trapping – providing efficient but very rarely occurring beaming of radio emission towards an observer, coupled with any other, also rare but powerful, phenomenon providing a strong enough initial ‘primary’ radio burst, may be responsible for the ultra-rare appearance of FRBs.