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Compton dragged gamma-ray bursts: the spectrum
Authors:Gabriele Ghisellini  Davide Lazzati  Annalisa Celotti  Martin J Rees
Institution:Institute of Astronomy, Madingley Road, Cambridge CB3 0HA;Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel;Astrophysics Group, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE;Departamento de Astronomia, Instituto Astronomico e Geofisico da USP, Av Miguel Stefano 4200, 04301-904 São Paulo, Brazil
Abstract:Recently several studies have jointly analysed data from different cosmological probes with the motivation of estimating cosmological parameters. Here we generalize this procedure to allow freedom in the relative weights of various probes. This is done by including in the joint χ 2 function a set of 'hyper-parameters', which are dealt with using Bayesian considerations. The resulting algorithm, which assumes uniform priors on the log of the hyper-parameters, is very simple: instead of minimizing     (where     is per data set j ) we propose to minimize     (where N j is the number of data points per data set j ). We illustrate the method by estimating the Hubble constant H 0 from different sets of recent cosmic microwave background (CMB) experiments (including Saskatoon, Python V, MSAM1, TOCO and Boomerang ). The approach can be generalized for combinations of cosmic probes, and for other priors on the hyper-parameters.
Keywords:methods: statistical  cosmic microwave background  cosmology: observations
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