Global 21cm Absorption Signal from Superconducting Cosmic Strings

Understand

Superconducting cosmic strings emit electromagnetic waves between the times of recombination and reionization.

• Hence, they have an effect on the global 21cm signal.
• We compute the resulting absorption features, focusing on strings with critical current, study their dependence on the string tension $\mu$, and compare with observational results.
• For string tensions in the range of $G \mu = 10^{-10}$, where $G$ is Newton's gravitational constant, there is an interesting amplification of the two characteristic absorption features, one during the cosmic dawn, $z \lesssim 30$, and the other during the cosmic dark age, $z \sim 80$, the former being comparable in amplitude to what was observed by the EDGES experiment.