The nature of fast radio bursts
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Date
2026-03-31
Authors
Long, Killian
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Publisher
University College Cork
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Abstract
The origin of fast radio bursts (FRBs) is a major open question in the field of astrophysics. We propose that FRBs are produced by synchrotron maser emission (SME) that occurs as a result of non-resonant interactions between Alfv´en waves and relativistic plasma. We examine the results of such an interaction, demonstrating that the particles gain significant amounts of kinetic energy through pitch-angle scattering. We show that the interaction forms the necessary population inversions for SME across a wide range of magnetisations and temperatures and examine how the properties of the plasma change as a result of the interaction. We calculate the resulting growth rates and peak frequencies of SME in such a scenario, and show that the mechanism can produce FRBs in the relativistic wind of a magnetar. We determine the lower limits on the wind Lorentz factors (γw ≳ 310) necessary to explain observed FRBs. Emission is possible at temperatures of θ = kBT/mc2 ≲ 0.02. We further examine the periods and magnetic fields of the central magnetar and demonstrate that the optimal values of these properties align with the observed magnetar population, provided that the magnetosphere is disturbed by the flaring activity. These results allow the properties of the environment such as temperature and magnetisation to be probed from the observed FRB frequency and luminosity.
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Keywords
Astrophysics , Fast radio bursts , Plasma physics
Citation
Long, K. 2026. The nature of fast radio bursts. PhD Thesis, University College Cork.