Kinetic-energy limits eliminate external-shock and light-cylinder FRB models
Model-independent kinetic-luminosity and brightness-temperature constraints rule out external and light-cylinder FRB scenarios. Only near-surface magnetospheric models with in-situ acceleration remain consistent with data, provided coherent waves can escape the magnetosphere. The analysis quantifies physical limits rarely addressed in observational FRB literature.
The arXiv preprint derives model-independent bounds on emitting-region density, radius and Lorentz factor from observed FRB luminosities and durations. These bounds are applied uniformly to three model classes without assuming specific radiation mechanisms. External shocks fail because the upstream wind remains optically thick to induced Compton scattering regardless of wind Lorentz factor or magnetization; escape routes either drop efficiency below 10^{-5} or broaden the spectrum beyond observed values. Light-cylinder forced reconnection supplies continuous acceleration yet converts only a tiny fraction of energy into coherent radio waves. Inner-magnetospheric models survive if particles are re-accelerated within R less than or equal to 10^{10} cm by magnetar-strength parallel electric fields.
Beniamini: Coherent escape calculations will show transmission fractions above 0.1 only for emission altitudes below 5 stellar radii within 18 months.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2606.25035)
- [2]Supporting Source(https://arxiv.org/abs/2204.06012)