On the Ly-alpha emission from gamma-ray burst host galaxies: evidence for low metallicities
Abstract
We report on the results of a search for Ly-alpha emission from the host galaxy of the z=2.140 GRB 011211 and other galaxies in its surrounding field. We detect Ly-alpha emission from the host as well as from six other galaxies in the field. The restframe equivalent width of the Ly-alpha line from the GRB 011211 host is about 21 AA. This is the fifth detection of Ly-alpha emission out of five possible detections from GRB host galaxies, strongly indicating that GRB hosts, at least at high redshifts, are Ly-alpha emitters. This is intriguing as only about 25% of the Lyman-Break selected galaxies at similar redshifts have Ly-alpha emission lines with restframe equivalent width larger than 20 AA. 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 Ly-alpha emitters at the faint end of the luminosity function for high-z galaxies. Of these, the current evidence seems to favour i).
Cite
@article{arxiv.astro-ph/0306403,
title = {On the Ly-alpha emission from gamma-ray burst host galaxies: evidence for low metallicities},
author = {J. P. U. Fynbo and P. Jakobsson and P. Moller and J. Hjorth and B. Thomsen and M. I. Andersen and A. S. Fruchter and J. Gorosabel and S. T. Holland and C. Ledoux and H. Pedersen and J. E. Rhoads and M. Weidinger and R. A. M. J. Wijers},
journal= {arXiv preprint arXiv:astro-ph/0306403},
year = {2008}
}
Comments
5 pages, 3 figures. Accepted for publication in A&A Letters