GRB3 - GRBs and Host Galaxies |
Speaker_ |
Arkhangelskaja, Irene |
Talk _ |
The analysis of GRB redshift distribution. |
Abstract _ |
First time the gamma ray burst redshift was defined in 1997 for GRB970228 and it shown that origin of this burst located at cosmology distanse scale. At present time the volume of GRB set with known redshift consists of approximately 80 bursts, most part of them were localised by SWIFT. The GRB redshift distribution is presented and its shape is discussed. Analysis of one peak approximation of GRB redshift distribution have shown that it has very heavy tail which consist of 25% of set of volume. As example of real uniform set the shape of normalized z-distribution for first 604 QSO from 2QZ_6QZ catalog is analysed and it is shown that only 1% of set of volume must be in the tail on the level comparable with tail of GRB redshift distribution. Such shape of distribution allows to make conclusion that this set is not uniform and at least two subgroups present in GRB redshift distribution at 95% confidence level which limited by volume of GRB set with known redshift. This conclusion confirmed by analysis of hi-square for two peak function approximation, which gives more significant result than one peak fit (95% and 80% correspondly). |