Measuring ΩM and ΩΛ with long-duration gamma-ray bursts

Gamma-ray bursts (GRBs) are one of the most luminous events in the Universe. In addition, the Universe itself is almost transparent to γ -rays, making GRBs detectable up to very high redshifts. As a result, GRBs are very suitable to probe the cosmological parameters. This work shows the potential of long-duration GRBs for measuring the cosmological parameters ΩM and ΩΛ by comparing the observed log N -log P distribution with the theoretical one. Provided that the GRBs rate and luminosity function are well determined, the best values and 1σ confidence intervals obtained are ΩM = 0.22+0.05–0.03 and ΩΛ = 1.06+0.05–0.10. Finally, a set of simulations show the ability of the method to measure ΩM and ΩΛ (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)