TY - JOUR
T1 - The warm, the excited, and the molecular gas
T2 - GRB 121024A shining through its star-forming galaxy
AU - Friis, M.
AU - De Cia, A.
AU - Krühler, T.
AU - Fynbo, J. P.U.
AU - Ledoux, C.
AU - Vreeswijk, P. M.
AU - Watson, D. J.
AU - Malesani, D.
AU - Gorosabel, J.
AU - Starling, R. L.C.
AU - Jakobsson, P.
AU - Varela, K.
AU - Wiersema, K.
AU - Drachmann, A. P.
AU - Trotter, A.
AU - Thöne, C. C.
AU - De Ugarte Postigo, A.
AU - D'Elia, V.
AU - Elliott, J.
AU - Maturi, M.
AU - Goldoni, P.
AU - Greiner, J.
AU - Haislip, J.
AU - Kaper, L.
AU - Knust, F.
AU - LaCluyze, A.
AU - Milvang-Jensen, B.
AU - Reichart, D.
AU - Schulze, S.
AU - Sudilovsky, V.
AU - Tanvir, N.
AU - Vergani, S. D.
N1 - Publisher Copyright: © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2015/5/1
Y1 - 2015/5/1
N2 - We present the first reported case of the simultaneous metallicity determination of a gamma-ray burst (GRB) host galaxy, from both afterglow absorption lines as well as strong emission-line diagnostics. Using spectroscopic and imaging observations of the afterglow and host of the long-duration Swift GRB 121024A at z = 2.30, we give one of the most complete views of a GRB host/environment to date. We observe a strong damped Lyα absorber (DLA) with a hydrogen column density of log N(Hi) = 21.88 ± 0.10, H2 absorption in the Lyman-Werner bands (molecular fraction of log(f) ≈ -1.4; fourth solid detection of molecular hydrogen in a GRB-DLA), the nebular emission lines Ha, Hβ, [O II], [O III] and [N II], as well as metal absorption lines. We find aGRB host galaxy that is highly star forming (SFR ~ 40M⊙ yr-1), with a dust-corrected metallicity along the line of sight of [Zn/H]corr =-0.6 ± 0.2 ([O/H] ~ -0.3 from emission lines), and a depletion factor [Zn/Fe] = 0.85 ± 0.04. The molecular gas is separated by 400 km s-1 (and 1-3 kpc) from the gas that is photoexcited by the GRB. This implies a fairly massive host, in agreement with the derived stellar mass of log(M*/M⊙) = 9.9-0.3+0.2. We dissect the host galaxy by characterizing its molecular component, the excited gas, and the line-emitting star-forming regions. The extinction curve for the line of sight is found to be unusually flat (RV ~ 15). We discuss the possibility of an anomalous grain size distributions. We furthermore discuss the different metallicity determinations from both absorption and emission lines, which gives consistent results for the line of sight to GRB 121024A.
AB - We present the first reported case of the simultaneous metallicity determination of a gamma-ray burst (GRB) host galaxy, from both afterglow absorption lines as well as strong emission-line diagnostics. Using spectroscopic and imaging observations of the afterglow and host of the long-duration Swift GRB 121024A at z = 2.30, we give one of the most complete views of a GRB host/environment to date. We observe a strong damped Lyα absorber (DLA) with a hydrogen column density of log N(Hi) = 21.88 ± 0.10, H2 absorption in the Lyman-Werner bands (molecular fraction of log(f) ≈ -1.4; fourth solid detection of molecular hydrogen in a GRB-DLA), the nebular emission lines Ha, Hβ, [O II], [O III] and [N II], as well as metal absorption lines. We find aGRB host galaxy that is highly star forming (SFR ~ 40M⊙ yr-1), with a dust-corrected metallicity along the line of sight of [Zn/H]corr =-0.6 ± 0.2 ([O/H] ~ -0.3 from emission lines), and a depletion factor [Zn/Fe] = 0.85 ± 0.04. The molecular gas is separated by 400 km s-1 (and 1-3 kpc) from the gas that is photoexcited by the GRB. This implies a fairly massive host, in agreement with the derived stellar mass of log(M*/M⊙) = 9.9-0.3+0.2. We dissect the host galaxy by characterizing its molecular component, the excited gas, and the line-emitting star-forming regions. The extinction curve for the line of sight is found to be unusually flat (RV ~ 15). We discuss the possibility of an anomalous grain size distributions. We furthermore discuss the different metallicity determinations from both absorption and emission lines, which gives consistent results for the line of sight to GRB 121024A.
KW - Galaxies: abundances
KW - Gamma-ray burst: individual: GRB 121024A
UR - https://www.scopus.com/pages/publications/84938262761
U2 - 10.1093/mnras/stv960
DO - 10.1093/mnras/stv960
M3 - Article
SN - 0035-8711
VL - 451
SP - 167
EP - 183
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -