Constraints on Superconducting Cosmic Strings from Early Reionization
  Electromagnetic radiation from superconducting cosmic string loops can reionize neutral hydrogen in the universe at very early epochs, and affect the cosmic microwave background (CMB) temperature and polarization correlation functions at large angular scales. We constrain the string tension and current using WMAP7 data, and compare with earlier constraints that employed CMB spectral distortions. Over a wide range of string tensions, the current on the string has to be less than 10^7 GeV. 
Hiroyuki Tashiro, Eray Sabancilar, Tanmay Vachaspati
astro-ph.CO hep-ph hep-th