VLT identification of the optical afterglow of the gamma-ray burst GRB000131 at z=4.50

M.I. Andersen, J. Hjorth, B.L. Jesen, L.K. Hunt, J. Gorosabel, P. Møller, J. Fynbo, R.M. Kippen, B. Thomsen, F.L. Olsen, L. Christensen, M. Vestergaard, N. Masetti, E. Palazzi, K. Hurley, T. Cline, L. Kaper, A.O. Jaunsen

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Abstract

We report the discovery of the gamma-ray burst GRB 000131 and its optical afterglow. The optical identification was made with the VLT 84 hours after the burst following a BATSE detection and an Inter Planetary Network localization. GRB 000131 was a bright, long-duration GRB, with an apparent precursor signal 62 s prior to trigger. The afterglow was detected in ESO VLT, NTT, and DK1.54m follow-up observations. Broad-band and spectroscopic observations of the spectral energy distribution reveals a sharp break at optical wavelengths which is interpreted as a Ly alpha absorption edge at 6700 Angstrom. This places GRB 000131 at a redshift of 4.500 +/- 0.015. The inferred isotropic energy release in gamma rays alone was similar to 10(54) erg (depending on the assumed cosmology). The rapid power-law decay of the afterglow (index alpha = 2.25, similar to bursts with a prior break in the lightcurve), however, indicates collimated outflow which relaxes the energy requirements by a factor of < 200. The afterglow of GRB 000131 is the first to be identified with an 8-m class telescope.
Original languageEnglish
JournalAstronomy & Astrophysics
Volume364
Issue number1
Pages (from-to)L54-L61
ISSN0004-6361
Publication statusPublished - 2000

Cite this

Andersen, M. I., Hjorth, J., Jesen, B. L., Hunt, L. K., Gorosabel, J., Møller, P., Fynbo, J., Kippen, R. M., Thomsen, B., Olsen, F. L., Christensen, L., Vestergaard, M., Masetti, N., Palazzi, E., Hurley, K., Cline, T., Kaper, L., & Jaunsen, A. O. (2000). VLT identification of the optical afterglow of the gamma-ray burst GRB000131 at z=4.50. Astronomy & Astrophysics, 364(1), L54-L61.