Cosmic strings and gravitational waves

Cosmic string networks are expected to generate a characteristic stochastic gravitational wave background that may be within the reach of current and upcoming gravitational wave detectors. A detection of this spectrum would provide invaluable information about the physics of the early universe, as it would allow us to probe the sequence of phase transitions that happened in the distant past. Here, I review the emission of gravitational waves by Nambu–Goto cosmic strings—thin cosmic strings that couple strongly to gravity only—and by superconducting strings—strings that carry electromagnetic currents. A comparison between the stochastic gravitational wave background predicted in these two very distinct string-forming scenarios reveals that this spectrum may have signatures that may allows us to discriminate between them observationally. The stochastic gravitational wave background generated by cosmic string networks may then enable us to uncover not only the energy-scale of the string-forming phase transition, but the underlying particle physics scenario as well.