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VLT/X-shooter spect...
VLT/X-shooter spectroscopy of the GRB 090926A afterglow
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D'Elia, V. (författare)
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Fynbo, J. P. U. (författare)
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Covino, S. (författare)
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visa fler...
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Goldoni, P. (författare)
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Jakobsson, P. (författare)
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Matteucci, F. (författare)
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Piranomonte, S. (författare)
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- Sollerman, J. (författare)
- Stockholms universitet,Institutionen för astronomi,Oskar Klein-centrum för kosmopartikelfysik (OKC)
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Thöne, C. C. (författare)
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Vergani, S. D. (författare)
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Vreeswijk, P. M. (författare)
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Watson, D. J. (författare)
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Wiersema, K. (författare)
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Zafar, T. (författare)
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de Ugarte Postigo, A. (författare)
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Flores, H. (författare)
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Hjorth, J. (författare)
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Kaper, L. (författare)
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Levan, A. J. (författare)
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Malesani, D. (författare)
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Milvang-Jensen, B. (författare)
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Pian, E. (författare)
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Tagliaferri, G. (författare)
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Tanvir, N. R. (författare)
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(creator_code:org_t)
- 2010-11-15
- 2010
- Engelska.
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 523, s. 36-
- Relaterad länk:
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https://www.aanda.or...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Aims: The aim of this paper is to study the environment and intervening absorbers of the gamma-ray burst GRB 090926A through analyzing optical spectra of its afterglow. Methods: We analyzed medium-resolution spectroscopic observations (R = 10 000, corresponding to 30 km s-1, S/N = 15-30 and wavelength range 3000-25 000) of the optical afterglow of GRB 090926A, taken with X-shooter at the VLT ~22 h after the GRB trigger. Results: The spectrum shows that the ISM in the GRB host galaxy at z = 2.1071 is rich in absorption features, with two components contributing to the line profiles. In addition to the ground state lines, we detect C ii, O i, Si ii, Fe ii, and Ni ii-excited absorption features, which we used to derive information on the distance between the host absorbing gas and the site of the GRB explosion. The distance of component I is found to be 2.40 ± 0.15 kpc, while component II is located far away from the GRB, possibly at ~5 kpc. These values are compatible with those found for other GRBs. The hydrogen column density associated to GRB 090926A is log NH/cm -2 = 21.60 ± 0.07, and the metallicity of the host galaxy is in the range [X/H] = -2.5 to -1.9 with respect to the solar values, i.e., among the lowest values ever observed for a GRB host galaxy. A comparison with galactic chemical evolution models has suggested that the host of GRB090926A is likely to be a dwarf-irregular galaxy. No emission lines were detected, but a Hα flux in emission of 9 × 10-18 erg s-1 cm-2 (i.e., a star-formation rate of 2 M_ȯ yr-1), which is typical of many GRB hosts, would have been detected in our spectra, and thus emission lines are well within the reach of X-shooter. We put an upper limit to the H molecular fraction of the host galaxy ISM, which is f < 7 × 10-7. The continuum has been fitted assuming a power-law spectrum, with a spectral index of β = 0.89-0.02+0.02. The best fit does essentially not require any intrinsic extinction because EB-V < 0.01 mag adopting a SMC extinction curve. Finally, the line of sight of GRB 090926A presents four weak intervening absorption systems in the redshift range 1.24 < z < 1.95. Based on observations collected at the European Southern Observatory, ESO, the VLT/Kueyen telescope, Paranal, Chile, during the science verification phase, proposal code: 060-9427(A).
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- ISM: abundances
- ISM: atoms
- galaxies: star formation
- line: profiles
- techniques: spectroscopic
- atomic processes
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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Till lärosätets databas
- Av författaren/redakt...
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D'Elia, V.
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Fynbo, J. P. U.
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Covino, S.
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Goldoni, P.
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Jakobsson, P.
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Matteucci, F.
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visa fler...
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Piranomonte, S.
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Sollerman, J.
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Thöne, C. C.
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Vergani, S. D.
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Vreeswijk, P. M.
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Watson, D. J.
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Wiersema, K.
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Zafar, T.
-
de Ugarte Postig ...
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Flores, H.
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Hjorth, J.
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Kaper, L.
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Levan, A. J.
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Malesani, D.
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Milvang-Jensen, ...
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Pian, E.
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Tagliaferri, G.
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Tanvir, N. R.
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visa färre...
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Stockholms universitet