GRB 050904 : A very high redshift gamma ray burst


We report near simultaneous multi-color (RIY JHK) observations made with the MAGNUM 2m telescope of the gamma ray burst GRB 050904 detected by the SWIFT satellite. The spectral energy distribution shows a very large break between the I and J bands. Using intergalactic transmissions measured from high redshift quasars we show that the observations place a 95% confidence lower limit of z = 6.18 on the object consistent with a later measured spectroscopic redshift of 6.29 obtained by Kawai et al. (2005) with the Subaru telescope. We show that the break strength in the R and I bands is consistent with that measured in the quasars. Finally we consider the implications for the star formation history at high redshift. Subject headings: cosmology: observations — gamma-rays: bursts — galaxies: distances and redshifts

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@inproceedings{Price2005GRB0, title={GRB 050904 : A very high redshift gamma ray burst}, author={P . A . Price and Lennox L. Cowie and Takeo Minezaki and Brian P Schmidt and Antoinette Songaila and Yotsumi Yoshii}, year={2005} }