Description
Nearly two decades after their discovery, the origin of fast radio bursts (FRBs) remains a mystery.
To date their bright, coherent radio emission has no detected counterparts beyond the radio band,
with the only exception of FRB-like flares emitted by the galactic magnetar SGR 1935+215. The
latter lend support to the proposed association of FRB sources with a cosmic population of magnetars.
I will summarize the main properties of FRB emission, and introduce our novel interpretation
in terms of strong gravitational lensing of neutron star (NS) flares due to the NS gravitational field,
i.e. the gravitational self-lensing (GSL) model. I show how this idea explains in a unified picture
the large FRB luminosities, the co-existence of rare repeaters and more numerous one-off sources,
and their overall energy budget, allowing at the same time to bridge the gap between the apparent
paucity of FRBs in the local universe and their comparatively large all-sky rate. Moreover, the
GSL model accounts for (a) the double-peaked energy distribution of individual FRBs observed in
the most active repeaters, in terms of a simple, pulsar-like emission geometry, and (b) the redshift
(and fluence) distribution of FRBs in the first CHIME catalog, in terms of a cosmic population –
consistent with magnetars - following the star formation history.