Measuring Ω M and Ω Λ 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 Ω M and Ω Λ 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 1 σ confidence intervals obtained are Ω M = 0.22 +0.05 –0.03 and Ω Λ = 1.06 +0.05 –0.10 . Finally, a set of simulations show the ability of the method to measure Ω M and Ω Λ (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)