GRB 050904 at red shift 6.3: Observations of the oldest cosmic explosion after the Big Bang

G. Tagliaferri, L. A. Antonelli, G. Chincarini, A. Fernández-Soto, D. Malesani, M. Della Valle, P. D'Avanzo, A. Grazian, V. Testa, S. Campana, S. Covino, F. Fiore, L. Stella, A. J. Castro-Tirado, J. Gorosabel, D. N. Burrows, M. Capalbi, G. Cusumano, M. L. Conciatore, V. D'EliaP. Filliatre, D. Fugazza, N. Gehrels, P. Goldoni, D. Guetta, S. Guziy, E. V. Held, K. Hurley, G. L. Israel, M. Jelínek, D. Lazzati, A. López-Echarri, A. Melandri, I. F. Mirabel, M. Moles, A. Moretti, K. O. Mason, J. Nousek, J. Osborne, L. J. Pellizza, R. Perna, S. Piranomonte, L. Piro, A. De Ugarte Postigo, P. Romano

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111 Scopus citations


We present optical and near-infrared observations of the afterglow of the gamma-ray burst GRB 050904. We derive a photometric redshift z = 6.3, estimated from the presence of the Lyman break falling between the I and J filters. This is by far the most distant GRB known to date. Its isotropic-equivalent energy is 3.4 × 1053 erg in the rest-frame 110-1100 keV energy band. Despite the high redshift, both the prompt and the afterglow emission are not peculiar with respect to other GRBs. We find a break in the J-band light curve at tb = 2.6 ± 1.0 d (observer frame). If we assume this is the jet break, we derive a beaming-corrected energy Eγ ∼ (4 ÷ 12) × 1051 erg. This limit shows that GRB 050904 is consistent with the Amati and Ghirlanda relations. This detection is consistent with the expected number of GRBs at z > 6 and shows that GRBs are a powerful tool to study the star formation history UD to very high redshift.

Original languageEnglish (US)
Pages (from-to)L1-L5
JournalAstronomy and Astrophysics
Issue number1
StatePublished - 2005

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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