Are GRB 090423 and Similar bursts due to Superconducting Cosmic strings?
  Superconducting cosmic strings may be able to power energetic gamma-ray bursts, in particular at high-redshifts ($z>6$). The ultra-relativistic outflows driven by the superconducting cosmic strings, however, seem too narrow to be consistent with the afterglow data of GRB 090423 and GRB 080913. 
Yu Wang, Yi-Zhong Fan, Da-Ming Wei
astro-ph.HE gr-qc hep-ph