Fast Radio Bursts with Extended Gamma-Ray Emission?

TL;DR

This paper explores the implications of gamma-ray counterparts to fast radio bursts (FRBs), discussing their potential origins, energy requirements, and the prospects for detection through gamma-ray, radio, and gravitational wave observations.

Contribution

It provides a comprehensive analysis of the possible models linking gamma-ray emission to FRBs and predicts observable signatures across multiple wavelengths and gravitational wave signals.

Findings

Gamma-ray detections can constrain FRB models.

Nearby, rare sources are needed if energy is from magnetic fields.

Radio afterglows from gamma-ray bright FRBs are detectable.

Abstract

We consider some general implications of bright gamma-ray counterparts to fast radio bursts (FRBs). We show that even if these manifest in only a fraction of FRBs, gamma-ray detections with current satellites (including Swift) can provide stringent constraints on cosmological FRB models. If the energy is drawn from the magnetic energy of a compact object such as a magnetized neutron star, the sources should be nearby and be very rare. If the intergalactic medium is responsible for the observed dispersion measure, the required gamma-ray energy is comparable to that of the early afterglow or extended emission of short gamma-ray bursts. While this can be reconciled with the rotation energy of compact objects, as expected in many merger scenarios, the prompt outflow that yields the gamma-rays is too dense for radio waves to escape. Highly relativistic winds launched in a precursor phase, and forming a wind bubble, may avoid the scattering and absorption limits and could yield FRB emission. Largely independent of source models, we show that detectable radio afterglow emission from gamma-ray bright FRBs can reasonably be anticipated. Gravitational wave searches can also be expected to provide useful tests.