Issue |
A&A
Volume 406, Number 3, August II 2003
|
|
---|---|---|
Page(s) | L63 - L66 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20030931 | |
Published online | 17 November 2003 |
Letter to the Editor
On the Lyα emission from gamma-ray burst host galaxies: Evidence for low metallicities *,**
1
Department of Physics and Astronomy, University of Aarhus, Ny Munkegade, 8000 Århus C, Denmark
2
Astronomical Observatory, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
3
European Southern Observatory, Karl Schwarzschild-Strasse 2, 85748 Garching, Germany
4
Astrophysikalisches Institut, 14482 Potsdam, Germany
5
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
6
Instituto de Astrofísica de Andalucía (IAA-CSIC), PO Box 03004, 18080 Granada, Spain
7
Department of Physics, University of Notre Dame, Notre Dame, IN 46556-5670, USA
8
European Southern Observatory, Casilla 19001, Santiago 19, Chile
9
University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
Corresponding author: J. P. U. Fynbo, jfynbo@phys.au.dk
Received:
30
April
2003
Accepted:
19
June
2003
We report on the results of a search for Lyα emission from the host
galaxy of the GRB 011211 and other galaxies in its surrounding field.
We detect Lyα emission from the host as well as from six other
galaxies in the field. The restframe equivalent width of the Lyα line
from the GRB 011211 host is about 21 Å. This is the fifth detection of
Lyα emission out of five possible detections from GRB host galaxies,
strongly indicating that GRB hosts, at least at high redshifts,
are Lyα emitters. This is intriguing as only ~25% of the
Lyman-Break selected galaxies at similar redshifts have Lyα emission
lines with restframe equivalent width larger than 20 Å. Possible
explanations are i) a preference for GRB progenitors to be metal-poor as
expected in the collapsar model, ii) an optical afterglow selection bias
against dusty hosts, and iii) a higher fraction of Lyα emitters at
the faint end of the luminosity function for high-z galaxies. Of these,
the current evidence seems to favour i).
Key words: gamma rays: bursts / galaxies: high redshift / techniques: photometric
© ESO, 2003
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