Magnetars with Low Magnetospheric Twist

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Summary Table
Category Progenitor Type Energy Mechanism Emission Mechanism Counterparts References Brief Comments
LF Radio HF Radio Microwave Terahertz Optical/IR X-rays Gamma-rays Gravitational Waves Neutrinos
Other Magnetars with Low Magnetospheric Twist Repeat Mag. reconnection Curv. Yes --- Maybe Maybe Maybe Maybe Unlikely detectable --- --- Unlikely to form in Galactic magnetars.

Definitions: LF Radio (3 MHz to 3 GHz); HF Radio (3 GHz to 30 GHz); Microwave (30 to 300 GHz)

Model Description

FRBs may be created in the closed field line regions of magnetar magnetospheres. Crustal slippage on the surface of the magnetar causes magnetic reconnection and thus particle acceleration, producing coherent emission. To allow emission to escape, the magnetars must have a low-density plasma in the closed field line regions, and hence must have low magnetospheric twist.

Observational Constraints

Unlikely to form in Galactic magnetars, which have a relatively high magnetospheric twist. Signals above a few MeV are expected to be suppressed by photon splitting and magnetic pair production in the magnetosphere.