TY - JOUR
T1 - GRB 021004: tomography of a gamma-ray burst progenitor and its host galaxy
AU - Castro-Tirado, Alberto Javier
AU - Moller, Palle
AU - Garcia-Segura, Guillermo Miguel
AU - Gorosabel, Javier
AU - Perez, Enrique
AU - de Ugarte Postigo, Antonio
AU - Solano, Enrique
AU - Barrado, David
AU - Klose, Sylvio
AU - Kann, David Alexander
AU - Castro Ceron, Jose Maria
AU - Kouveliotou, Chryssa
AU - Fynbo, Johan Peter Uldall
AU - Hjorth, Jens
AU - Pedersen, Holger
AU - Pian, Elena
AU - Rol, Evert
AU - Palazzi, Eliana
AU - Masetti, Nicola
AU - Tanvir, Nial R
AU - Vreeswijk, Paul Marijn
AU - Andersen, Michael Ingemann
AU - Fruchter, Andrew S
AU - Greiner, Jochen
AU - Wijers, Ralph A M J
AU - van den Heuvel, Edward P J
PY - 2010
Y1 - 2010
N2 - Aims. We analyse the distribution of matter around the progenitor star of gamma-ray burst GRB 021004 and the properties of its host galaxy with high-resolution echelle and near-infrared spectroscopy. Methods. Observations were taken by the 8.2 m Very Large Telescope with the Ultraviolet and Visual Echelle spectrograph (UVES) and the Infrared Spectrometer And Array Camera (ISAAC) between 10 and 14 h after the onset of the event. Results. We report the first detection of emission lines from a GRB host galaxy in the near-infrared, detecting Ha and the [O III] doublet. These allow us to independently measure the systemic redshift (z = 2.3304 +/- 0.0005), which is not contaminated by absorption as the Lya line is, and infer the host galaxy properties. From the visual echelle spectroscopy, we find several absorption-line groups spanning a range of about 3000 km s-1 in velocity relative to the redshift of the host galaxy. The absorption profiles are very complex with both velocity-broadened components extending over several 100 km s-1 and narrow lines with velocity widths of only 20 km s-1. By analogy with QSO absorption line studies, the relative velocities, widths, and degrees of ionization of the lines ( line- locking , ionization-velocity correlation ) show that the progenitor had both an extremely strong radiation field and several distinct mass-loss phases (winds). Conclusions. These results are consistent with GRB progenitors being massive stars, such as luminous blue variables (LBVs) or Wolf-Rayet stars, providing a detailed picture of the spatial and velocity structure of the GRB progenitor star at the time of explosion. The host galaxy is a prolific star-forming galaxy with a SFR of 40 M.
AB - Aims. We analyse the distribution of matter around the progenitor star of gamma-ray burst GRB 021004 and the properties of its host galaxy with high-resolution echelle and near-infrared spectroscopy. Methods. Observations were taken by the 8.2 m Very Large Telescope with the Ultraviolet and Visual Echelle spectrograph (UVES) and the Infrared Spectrometer And Array Camera (ISAAC) between 10 and 14 h after the onset of the event. Results. We report the first detection of emission lines from a GRB host galaxy in the near-infrared, detecting Ha and the [O III] doublet. These allow us to independently measure the systemic redshift (z = 2.3304 +/- 0.0005), which is not contaminated by absorption as the Lya line is, and infer the host galaxy properties. From the visual echelle spectroscopy, we find several absorption-line groups spanning a range of about 3000 km s-1 in velocity relative to the redshift of the host galaxy. The absorption profiles are very complex with both velocity-broadened components extending over several 100 km s-1 and narrow lines with velocity widths of only 20 km s-1. By analogy with QSO absorption line studies, the relative velocities, widths, and degrees of ionization of the lines ( line- locking , ionization-velocity correlation ) show that the progenitor had both an extremely strong radiation field and several distinct mass-loss phases (winds). Conclusions. These results are consistent with GRB progenitors being massive stars, such as luminous blue variables (LBVs) or Wolf-Rayet stars, providing a detailed picture of the spatial and velocity structure of the GRB progenitor star at the time of explosion. The host galaxy is a prolific star-forming galaxy with a SFR of 40 M.
UR - http://www.aanda.org/articles/aa/pdf/2010/09/aa13966-09.pdf
U2 - 10.1051/0004-6361/200913966
DO - 10.1051/0004-6361/200913966
M3 - Article
SN - 0004-6361
VL - 517
SP - 1
EP - 9
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
IS - 9
ER -