2005/01/31 by D. Xu, Z. G. Dai, Zi-Gao Dai +2
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/466509
published as Astrophys.J. 633 (2005) 603-610 · 26 pages including 6 figures, different methods compared, accepted for publication in ApJ
arxiv created 2005/07/21 · openalex publication_date 2005/11/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Three different methods of measuring cosmology with gamma-ray bursts (GRBs) have been proposed since a relation between the gamma-ray energy E γ of a GRB jet and the peak energy E p of the ν F ν spectrum in the burst frame was reported by Ghirlanda and coauthors. In method I, to calculate the probability for a favored cosmology, only the contribution of the E γ - E p relation that is already best-fitted for this cosmology is considered. We apply this method to a sample of 17 GRBs and obtain the mass density Ω M = 0.15 (1 σ) for a flat ΛCDM universe. In method II, to calculate the probability for some certain cosmology, contributions of all the possible E γ - E p relations that are best-fitted for their corresponding cosmologies are taken into account. With this method, we find a constraint on the mass density 0.14 < Ω M < 0.69 (1 σ) for a flat universe. In method III, to obtain the probability for some cosmology, contributions of all the possible E γ - E p relations associated with their unequal weights are considered. With this method, we obtain an inspiring constraint on the mass density 0.16 < Ω M < 0.45 (1 σ) for a flat universe and χ = 19.08/15 = 1.27 for the concordance model of Ω M = 0.27. Compared with the previous two methods, method III makes the observed 17 GRBs place much more stringent confidence intervals at the same confidence levels. Furthermore, we perform a Monte Carlo simulation and use a larger sample to investigate the cosmographic capabilities of GRBs with different methods. We find that a larger GRB sample could be used to effectively measure cosmology, no matter whether the E γ - E p relation is calibrated by low- z bursts or not. Ongoing observations of GRBs in the Swift era are expected to make the cosmological utility of GRBs progress from its babyhood into childhood.