VLT identification of the optical afterglow of the gamma-ray burst GRB 000131 at z=4.50

M. I. Andersen, J. Hjorth, H. Pedersen, B. L. Jensen, L. K. Hunt, J. Gorosabel, P. Moller, J. Fynbo, R. M. Kippen, B. Thomsen, L. F. Olsen, L. Christensen, Marianne 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 A. This places GRB 000131 at a redshift of 4.500 +/- 0.015. The inferred isotropic energy release in gamma rays alone was approximately 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
Original languageEnglish
JournalAstronomy & Astrophysics
Volume364
Pages (from-to)L54-L61
ISSN0004-6361
Publication statusPublished - 17 Oct 2000

Keywords

  • astro-ph

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