Gas and dust properties in the afterglow spectra of GRB 050730
Abstract
We present early WHT ISIS optical spectroscopy of the afterglow of gamma-ray burst GRB 050730. The spectrum shows a DLA system with the highest measured hydrogen column to date: N(H I) = 22.1 ± 0.1 at the third-highest GRB redshift z = 3.968. Our analysis of the Swift XRT X-ray observations of the early afterglow show X-ray flares accompanied by decreasing X-ray absorption. From both the optical and the X-ray spectra we constrain the dust and gas properties of the host galaxy. We find the host to be a low metallicity galaxy, with low dust content. Much of the X-ray absorbing gas is situated close to the GRB, whilst the H I absorption causing the DLA is most likely located further out.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 2005
- DOI:
- 10.1051/0004-6361:200500181
- arXiv:
- arXiv:astro-ph/0508237
- Bibcode:
- 2005A&A...442L..21S
- Keywords:
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- gamma rays: bursts;
- galaxies: distances and redshifts;
- cosmology: observations;
- Astrophysics
- E-Print:
- 5 pages, 2 figures. Accepted for A&