The host galaxy of GRB 990712 *,**
Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
2 Niels Bohr Institute, Astronomical Observatory, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
3 Instituto de Astrofísica de Andalucía, IAA-CSIC, Granada, Spain
4 Laboratorio de Astrofísica Espacial y Física Fundamental (LAEFF-INTA), PO Box 50727, 28080 Madrid, Spain
5 Danish Space Research Institute, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
6 European Southern Observatory, Casilla 19, Santiago, Chile
7 Astronomical Institute "Anton Pannekoek”, University of Amsterdam & Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
8 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Corresponding author: L. Christensen, firstname.lastname@example.org
Accepted: 20 September 2003
We present a comprehensive study of the host galaxy of GRB 990712, involving ground-based photometry, spectroscopy, and HST imaging. The broad-band s photometry is used to determine the global spectral energy distribution (SED) of the host galaxy. Comparison with that of known galaxy types shows that the host is similar to a moderately reddened starburst galaxy with a young stellar population. The estimated internal extinction in the host is and the star-formation rate (SFR) from the UV continuum is 1.3 ± 0.3 M (not corrected for the effects of extinction). Other galaxy template spectra than starbursts failed to reproduce the observed SED. We also present VLT spectra leading to the detection of Hα from the GRB host galaxy. A SFR of 2.8 ± 0.7 M is inferred from the Hα line flux, and the presence of a young stellar population is supported by a large equivalent width. Images from HST/STIS show that the host has two separate knots, which could be two distinct star-forming regions.
Key words: gamma rays: bursts / galaxies: hosts / galaxies: star formation
Based on observations collected at the European Southern Observatory, La Silla, with the ESO 3.6 m telescope, NTT, and VLT (ESO Programmes 165.H-0464(I) and 165.H-0464(E), and 265.D-5742(B)) by the Gamma-Ray Burst Afterglow Collaboration at ESO (GRACE) group. Further based on observations with the Danish 1.5 m telescope.
© ESO, 2004