Gamma-ray Bursts as Dark Energy 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, $p= \omega \rho$. We find that this test yields rather disappointing results for the GCG model, being mainly sensitive to the total amount of matter present in the Universe in the case of the XCDM model. We also find that, within the framework of the XCDM model, a large sample of GRBs ($\geq 200$) may turn out to be quite useful to improve the forthcoming type Ia supernovae data. 
O. Bertolami P. T. Silva