Resumen

FIRMANI, C; AVILA-REESE, V; GHISELLINI, G  y  GHIRLANDA, G. Long gamma-ray burst prompt emission properties as a cosmological tool. Rev. mex. astron. astrofis [online]. 2007, vol.43, n.1, pp.203-216. ISSN 0185-1101.

Recently, a tight correlation among three quantities that characterize the prompt emission of long Gamma-Ray Bursts (GRBs) with known redshift z, was discovered (Firmani et al. 2006a). We use this correlation to construct the Hubble diagram (HD) with a sample of 19 GRBs in the broad range of z = 0.17 - 4.5, and carry out a full statistical analysis to constrain cosmological parameters (CPs). To optimally solve the problem of circularity, a Bayesian approach is applied. The main result is that the concordance ACDM cosmology is fully consistent with the GRB data at the level of several tests. If we assume the Λ cosmology, then we find and the flat-geometry case is within la. Assuming flatness, we find , and fixing Ω_m =0.28, we obtain a dark energy equation of state parameter , i.e. the ACDM model (w = -1) is within 1σ. Given the low number of usable GRBs we cannot yet constrain well the possible evolution of w = w(z). However, the case w(z) = -1 (ACDM) is consistent at the 68.3% CL with GRBs. It is shown also how a broad range of z's in the used sample improves the determination of CPs from the HD, which is the case of GRBs as distance indicators.

Palabras llave : COSMOLOGICAL PARAMETERS; COSMOLOGY: OBSERVATIONS; DISTANCE SCALE GAMMA RAYS: BURSTS.

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