GRB060614 is at High Redshift, So No New Class of Gamma-Ray Bursts is   Required
  Long duration Gamma-Ray Bursts (GRBs) have been strongly connected with core collapse supernovae, so it was surprising when the recent GRB060614 (with a reported redshift of 0.125) was found to have no visible supernova to deep limits. Three separate groups have reached the same conclusion that this event forces the existence of a new previously-unsuspected class of GRBs. The problem with this conclusion is that the redshift is not secure, as the measured galaxy emission lines simply give the redshift of the brightest galaxy near the line-of-sight to the GRB afterglow. Fortunately, eight different luminosity indicators are known which can give the luminosity (and hence redshift) of the GRB itself. In combination, these luminosity indicators have already proven to give redshifts with average one-sigma errors of 26% as based on 69 GRBs with spectroscopic redshifts. For GRB060614, the luminosity indicators all uniformly give a high luminosity for the burst which implies a high redshift. This can be seen by the spiky many-peaked light curve, the high E_{peak} value, the near-zero spectral lag, and the timing of the jet break. Quantitatively, we derive a redshift of 1.97 (1.44<z<2.81 one-sigma) from the eight luminosity indicators. Additional information from the detection of the afterglow in all Swift UVOT bands further constrains the redshift to be <1.71, so the final range of allowed redshift is 1.44<z<1.71, which readily explains why no supernova was visible. Thus, GRB060614 is at high redshift and is certainly not evidence for a new class of GRBs. 
Bradley E. Schaefer and Limin Xiao