Gamma Ray Bursts as Cosmological Probes
  We discuss the prospects of using Gamma Ray Bursts (GRBs) as high-redshift distance estimators, and consider their use in the study of two dark energy models, the Generalized Chaplygin Gas (GCG), a model for the unification of dark energy and dark matter, and the XCDM model, a model where a generic dark energy fluid like component is described by the equation of state, $p= \omega \rho$. Given that the GRBs range of redshifts is rather high, it turns out that they are not very sensitive to the dark energy component, being however, fairly good estimators of the amount of dark matter in the Universe. 
O. Bertolami, P. T. Silva