GRB 080913 at Redshift 6.7

Greiner, J.; Krühler, T.; Fynbo, J. P. U.; Rossi, A.; Schwarz, R.; Klose, S.; Savaglio, S.; Tanvir, N. R.; McBreen, S.; Totani, T.; Zhang, B. B.; Wu, X. F.; Watson, D.; Barthelmy, S. D.; Beardmore, A. P.; Ferrero, P.; Gehrels, N.; Kann, D. A.; Kawai, N.; Yoldaş, A. Küpcü; Mészáros, P.; Milvang-Jensen, B.; Oates, S. R.; Pierini, D.; Schady, P.; Toma, K.; Vreeswijk, P. M.; Yoldaş, A.; Zhang, B.; Afonso, P.; Aoki, K.; Burrows, D. N.; Clemens, C.; Filgas, R.; Haiman, Z.; Hartmann, D. H.; Hasinger, G.; Hjorth, J.; Jehin, E.; Levan, A. J.; Liang, E. W.; Malesani, D.; Pyo, T.-S.; Schulze, S.; Szokoly, G.; Terada, K.; Wiersema, K.
Bibliographical reference

The Astrophysical Journal, Volume 693, Issue 2, pp. 1610-1620 (2009).

Advertised on:
3
2009
Number of authors
47
IAC number of authors
0
Citations
208
Refereed citations
172
Description
We report on the detection by Swift of GRB 080913, and subsequent optical/near-infrared follow-up observations by GROND, which led to the discovery of its optical/NIR afterglow and the recognition of its high-z nature via the detection of a spectral break between the i' and z' bands. Spectroscopy obtained at the ESO-VLT revealed a continuum extending down to λ = 9400 Å, and zero flux for 7500 Å<λ < 9400 Å, which we interpret as the onset of a Gunn-Peterson trough at z = 6.695± 0.025 (95.5% confidence level), making GRB 080913 the highest-redshift gamma-ray burst (GRB) to date, and more distant than the highest-redshift QSO. We note that many redshift indicators that are based on promptly available burst or afterglow properties have failed for GRB 080913. We report on our follow-up campaign and compare the properties of GRB 080913 with bursts at lower redshift. In particular, since the afterglow of this burst is fainter than typical for GRBs, we show that 2 m class telescopes can identify most high-redshift GRBs.