Coherent curvature radiation: maximum luminosity and high-energy emission

TL;DR

This paper investigates the limits of coherent curvature radiation in neutron star environments, explaining high-brightness radio transients like pulsars and FRBs, and predicts associated X-ray emissions.

Contribution

It derives a maximum luminosity for coherent curvature radiation based on source parameters and links this mechanism to various high-energy astrophysical phenomena.

Findings

Maximum luminosity depends on magnetic field and spin period.

Coherent curvature radiation can explain all observed radio transient luminosities.

Predicted simultaneous X-ray emission from particle gyration.

Abstract

High brightness temperature radio transients such as pulsars and fast radio bursts require the coherent radiation of particles. The antenna class of coherent radiation models require a large number of charged particles radiating in phase, therefore the particles must be spatially confined and have well-aligned velocities. Given these necessary conditions, we look at the magnetic field induced by the currents associated with coherently emitting accelerated particles and consider the interaction between the radiating particles and the induced magnetic field. We find a maximum luminosity of coherent curvature radiation that depends on source parameters such as surface magnetic field and neutron star spin period. We find that coherent radio emission across all luminosities can be explained by coherent curvature radiation and suggest it could be universally responsible for both FRBs and extreme galactic sources. Using the Crab Pulsar as an example, we constrain the emission parameters and origin of the most extreme nanoshots to within 60km of the pulsar surface assuming coherent curvature radiation. In agreement with recent observations, we also predict simultaneous X-ray emission from small-scale particle gyration due to the induced field.