Constraints on superconducting cosmic strings from the global 21-cm signal before reionization

Electromagnetic radiation from the cusp region of superconducting cosmic strings leads to a radio excess in the photon spectrum in the early universe and can produce a deep absorption feature in the global 21 cm signal before the epoch of reionization. We study the constraints on the parameter space of superconducting strings which can be derived by demanding that the absorption feature is not larger in amplitude than what has recently been reported by the EDGES collaboration. We find a previously unconstrained region of high current, low tension strings would produce too strong of an absorption feature, and are thus ruled out by non-detection.