Neutral Cosmic Strings
| 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 | Neutral Cosmic Strings | Single | Cusp decay | -- | Yes | -- | -- | -- | -- | -- | GRB if jet aligned |
Yes | Yes | https://arxiv.org/pdf/1701.01109.pdf | High energy cosmic rays are also expected. |
Definitions: LF Radio (3 MHz to 3 GHz); HF Radio (3 GHz to 30 GHz); Microwave (30 to 300 GHz)
Model Description
Nambu-Goto (infinitely thin, idealised) cosmic strings generically form cusps, portions of the string which fold back onto themselves and move at the speed of light. The cusps decay, emitting a beam of coherent radiation. The decay particle can ostensibly be of any energy and frequency range, and so should extend down into radio bursts. Cusp decay from cosmic strings has been put forward to explain FRBs [285]. The event rate, timescale, and flux emitted are shown to be consistent with FRB data, however the relativistic effects on the cusp shape was not factored in. By taking this into account, cusp decay is in fact incompatible with current FRB data [286]. Cosmic strings are not ruled out by observations, and would necessarily include counterparts of other electromagnetic frequencies—specifically, GRBs [287], cosmic rays [288] and neutrinos [289]—and GWs.
Observational Constraints
To be filled in with updated draft