VLT/X-Shooter spectroscopy of the afterglow of the Swift GRB 130606A Chemical abundances and reionisation at z similar to 6
: Hartoog OE, Malesani D, Fynbo JPU, Goto T, Kruhler T, Vreeswijk PM, De Cia A, Xu D, Moller P, Covino S, D'Elia V, Flores H, Goldoni P, Hjorth J, Jakobsson P, Krogager JK, Kaper L, Ledoux C, Levan AJ, Milvang-Jensen B, Sollerman J, Sparre M, Tagliaferri G, Tanvir NR, Postigo AD, Vergani SD, Wiersema K, Datson J, Salinas R, Mikkelsen K, Aghanim N
Publisher: EDP SCIENCES S A
: 2015
: Astronomy and Astrophysics
: ASTRONOMY & ASTROPHYSICS
: ASTRON ASTROPHYS
: ARTN A139
: 580
: 15
: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/201425001
Conclusions. Our measurements confirm that the Universe is already predominantly ionised over the redshift range probed in this work, but was slightly more neutral at z > 5.6. GRBs are useful probes of the ionisation state of the IGM in the early Universe, but because of internal scatter we need a larger statistical sample to draw robust conclusions. The high [Si/Fe] in the host can be due to dust depletion, a-element enhancement, or a combination of both. The very high value of [Al/Fe] = 2.40 +/- 0.78 might be due to a proton capture process and is probably connected to the stellar population history. We estimate the host metallicity to be -1.7 < [M/H] < -0.9 (2%-13% of solar).
