A Flash in the dark: UVES/VLT high resolution spectroscopy of GRB afterglows
Sep, 200415 pages
Published in:
- Astrophys.J. 624 (2005) 853-867
e-Print:
- astro-ph/0409717 [astro-ph]
DOI:
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Abstract: (arXiv)
We present the first high resolution (R=20000--45000, corresponding to 14 km/s at 4200A to 6.6 km/s at 9000A) observations of the optical afterglow of Gamma Ray Bursts. GRB020813 and GRB021004 were observed by UVES@VLT 22.19 hours and 13.52 hours after the trigger, respectively. These spectra show that the inter--stellar matter of the GRB host galaxies is complex, with many components contributing to each main absorption system, and spanning a total velocity range of up to about 3000 km/s. Several narrow components are resolved down to a width of a few tens of km/s. In the case of GRB021004 we detected both low and high ionization lines. Combined with photoionization results obtained with CLOUDY, the ionization parameters of the various systems are consistent with a remarkably narrow range with no clear trend with system velocity. This can be interpreted as due to density fluctuations on top of a regular R^-2 wind density profile.- cosmology: observations
- galaxies: abundances
- galaxies: ISM
- gamma rays: bursts
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