Tiny EM Explosions

From FRB Theory Wiki
Jump to: navigation, search





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 Tiny EM Explosions Both Thin shell interactions Curv. Yes Yes -- -- -- -- Unlikely observable -- -- http://adsabs.harvard.edu/abs/2017ApJ...844..162T, http://adsabs.harvard.edu/abs/2017ApJ...844...65T None

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


Model Description

The collision of two relativistic macroscopic dipoles that form around the time of cosmic electroweak symmetry-breaking could cause a tiny explosion. Tiny electromagnetic explosions occur when the initial wavelength of the explosion is narrower than the wavelength of the radiation observed so the energy travels outwards in a very thin shell, and the surrounding charged particles are deflected (as opposed to reflected) by the magnetic field embedded in the expanding shell.

To retain the supporting electric field for cosmological timescales, these field structures must be superconducting, and are thus dubbed large superconducting dipoles (LSD) - the term "Large" is relative, and is used because the dipoles are macroscopic. The expanding relativistic magnetized shell from the explosion couples efficiently to a low-frequency, strong, superluminal EM wave in the surrounding plasma, allowing the emission to escape. Three emission mechanisms are possible: the reflection of an ambient static magnetic field by the conducting surface of the shell; direct linear conversion of the magnetic field in the shell; and the excitation of an EM wave if the surface of the shell becomes corrugated via the reconnection of the ejected magnetic field with the ambient magnetic field. The deceleration of the magnetic shell causes a higher frequency radio pulse and the thermal part of the explosion radiates Gamma-rays, however the latter are not expected to be detectable. The model accounts for repeating and non-repeating FRBs and for their observed differences in linear polarizations and RMs - the hydromagnetic drag on LSDs is weak in the ISM, and strong in high - density environments. As such, a slowly accreting SMBH may capture LSDs and group them in gravitationally bound cusps, within which the LSDs collide and create repeating FRBs. Here the high density plasma accounts for the high linear polarization and high RM observed in FRB 121102. The opposite is true for LSDs far from the SMBH; where the observed RM is low and signals are non-repeating, such as in FRB 150215, collisions are expected to take place in dark matter halos of galaxies.

Observational Constraints

--