THE METALLICITY AND DUST CONTENT OF A REDSHIFT 5 GAMMA-RAY BURST HOST GALAXY
/ Authors
M. Sparre, O. Hartoog, T. Krühler, T. Krühler, J. Fynbo, D. Watson, K. Wiersema, V. D’Elia, T. Zafar, P. Afonso
and 22 more authors
S. Covino, A. D. U. Postigo, A. D. U. Postigo, H. Flores, P. Goldoni, J. Greiner, J. Hjorth, P. Jakobsson, L. Kaper, S. Klose, A. Levan, D. Malesani, B. Milvang-Jensen, M. Nardini, S. Piranomonte, J. Sollerman, R. S'anchez-Ram'irez, S. Schulze, N. Tanvir, S. Vergani, S. Vergani, R. Wijers
/ Abstract
Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A, from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio (DTM), and extinction of the GRB host galaxy at z = 5.0. The host absorption system is a damped Lyα absorber with a very large neutral hydrogen column density of and a metallicity of [S/H] = −1.70 ± 0.10. It is the highest-redshift GRB with such a precise metallicity measurement. The presence of fine-structure lines confirms the z = 5.0 system as the GRB host galaxy and makes this the highest redshift where Fe ii fine-structure lines have been detected. The afterglow is mildly reddened with AV = 0.11 ± 0.04 mag, and the host galaxy has a DTM that is consistent with being equal to or lower than typical values in the Local Group.
Journal: The Astrophysical Journal