Very high column density and small reddening toward GRB 020124 at z = 3.20

J. Hjorth, P. Møller, J. Gorosabel, J. P.U. Fynbo, S. Toft, A. O. Jaunsen, A. A. Kaas, T. Pursimo, K. Torii, T. Kato, H. Yamaoka, A. Yoshida, B. Thomsen, M. I. Andersen, I. Burud, J. M. Castro Cerón, A. J. Castro-Tirado, A. S. Fruchter, L. Kaper, C. KouveliotouN. Masetti, E. Palazzi, H. Pedersen, E. Pian, J. Rhoads, E. Rol, N. R. Tanvir, P. M. Vreeswijk, R. A.M.J. Wijers, E. P.J. Van den Heuvel

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


We present optical and near-infrared observations of the dim afterglow of GRB 020124, obtained between 2 and 68 hr after the gamma-ray burst. The burst occurred in a very faint (R ≲ 29.5) damped Lyα absorber (DLA) at a redshift of z = 3.198 ± 0.004. The derived column density of neutral hydrogen is log(NH I) = 21.7 ± 0.2, and the rest-frame reddening is constrained to be E(B- V) < 0.065, i.e., AV < 0. 20 for standard extinction laws with Rv ≈ 3. The resulting dust-to-gas ratio is less than 11% of that found in the Milky Way but consistent with the SMC and high-redshift QSO DLAs, indicating a low metallicity and/or a low dust-to-metal ratio in the burst environment. A gray extinction law (large Rv), produced through preferential destruction of small dust grains by the gamma-ray burst, could increase the derived A v and dust-to-gas ratio. The dimness of the afterglow is, however, fully accounted for by the high redshift: if GRB 020124 had been at z = 1, it would have been approximately 1.8 mag brighter - in the range of typical bright afterglows.

Original languageEnglish (US)
Pages (from-to)699-705
Number of pages7
JournalAstrophysical Journal
Issue number2 I
StatePublished - Nov 10 2003
Externally publishedYes


  • Cosmology: observations
  • Dust, extinction
  • Galaxies: abundances galaxies: ISM
  • Gamma rays: bursts

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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