GRB 011121: A collimated outflow into wind-blown surroundings

J. Greiner, S. Klose, M. Salvato, A. Zeh, R. Schwarz, D. H. Hartmann, N. Masetti, B. Stecklum, G. Lamer, N. Lodieu, R. D. Scholz, C. Sterken, J. Gorosabel, I. Burud, J. Rhoads, I. Mitrofanov, M. Litvak, A. Sanin, V. Grinkov, M. I. AndersenJ. M. Castro Cerón, A. J. Castro-Tirado, A. Fruchter, J. U. Fynbo, J. Hjorth, L. Kaper, C. Kouveliotou, E. Palazzi, E. Pian, E. Rol, N. R. Tanvir, P. M. Vreeswijk, R. A.M.J. Wijers, E. Van den Heuvel

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


We report optical and near-infrared follow-up observations of GRB 011121 collected predominantly at ESO telescopes in Chile. We discover a break in the afterglow light curve after 1.3 days, which implies an initial jet opening angle of about 9°. The jet origin of this break is supported by the fact that the spectral energy distribution is achromatic during the first 4 days. During later phases, GRB 011121 shows significant excess emission above the flux predicted by a power law, which we interpret as additional light from an underlying supernova. In particular, the spectral energy distribution of the optical transient approximately 2 weeks after the burst is clearly not of power-law type but can be presented by a blackbody with a temperature of ∼6000 K. The deduced parameters for the decay slope and the spectral index favor a wind scenario, i.e., an outflow into a circumburst environment shaped by the stellar wind of a massive gamma-ray burst (GRB) progenitor. Because of its low redshift of z = 0.36, GRB 011121 has been the best example for the GRB-supernova connection until GRB 030329 and provides compelling evidence for a circumburster wind region expected to exist if the progenitor was a massive star.

Original languageEnglish (US)
Pages (from-to)1223-1237
Number of pages15
JournalAstrophysical Journal
Issue number2 I
StatePublished - Dec 20 2003
Externally publishedYes


  • Gamma rays: bursts
  • Supernovae: general
  • Techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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