Upper Field Strength Limit of Fast Radio Bursts

TL;DR

This paper uses particle-in-cell simulations to establish an upper limit on the magnetic field strength of fast radio bursts at their source, suggesting that fields stronger than 3×10^12 V/cm are dampened by pair plasma formation.

Contribution

It introduces a novel simulation-based approach to determine the maximum possible magnetic field strength of FRBs at their source.

Findings

Fields stronger than 3×10^12 V/cm are dampened by pair plasma formation.

Quantum cascade effects significantly reduce the escape of ultra-strong GHz radio pulses.

An upper limit on FRB source field strength is proposed based on simulation results.

Abstract

Fast radio bursts (FRBs) are cosmological radio transients with unclear generation mechanism. Known characteristics such as their luminosity, duration, spectrum and repetition rate, etc. suggest that FRBs are powerful coherent radio signals at GHz frequencies, but the status of FRBs near source remain unknown. As an extreme astronomical event, FRBs should be accompanied by energy -- comparable or even more powerful x/{\gamma}-ray counterparts. Here, particle-in-cell simulations of ultra-strong GHz radio pulse interaction with GeV photons show that at 3*10^12V/cm field-strengths, quantum cascade can generate dense pair plasmas, which greatly dampen the radio pulse. Thus, in the presence of GeV photons in the source region, GHz radio pulses stronger than 3*10^12V/cm cannot escape. This result indicates an upper field-strength limit of FRB at the source.