Electromagnetic Emission from Blitzars and Its Impact on Non-repeating Fast Radio Bursts

Abstract

It has been suggested that a non-repeating fast radio burst (FRB) represents the final signal of a magnetized neutron star collapsing to a black hole. In this model, a supramassive neutron star supported by rapid rotation, will collapse to a black hole several thousand to million years after its birth, as a result of spin-down. The collapse violently snaps the magnetic field lines anchored on the stellar surface, thus producing an electromagnetic pulse that will propagate outward and accelerate electrons, thus producing a massive radio burst, i.e., a "blitzar." We present a systematic study of the gravitational collapse of rotating and magnetized neutron stars, with special attention to far-field evolution at late times after the collapse. By considering a series of neutron stars with rotation ranging from zero to millisecond periods and different magnetic-field strengths, we show that the blitzar emission is very robust and always characterized by a series sub-millisecond pulses decaying exponentially in amplitude. The luminosity and energy released when the magnetosphere is destroyed are well-reproduced by a simple expression in terms of the stellar magnetic field and radius. Finally, we assess the occurrence of pair production during a blitzar scenario. We conclude that, for typical magnetic-field strengths of 10¹² G and spin frequencies of a few Hz, pair production is suppressed. Overall, the very good match between the results of the simulations and the luminosities normally observed for FRBs lends credibility to the blitzar model as a simple yet plausible explanation for the phenomenology of non-repeating FRBs.

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