Evidence for a supernova associated with the X-ray flash 020903

D. Bersier*, A. S. Fruchter, L. G. Strolger, J. Gorosabel, A. Levan, I. Burud, J. E. Rhoads, A. C. Becker, A. Cassan, R. Chornock, S. Covino, R. S. De Jong, D. Dominis, A. V. Filippenko, J. Hiorth, J. Holmberg, D. Malesani, B. Mobasher, K. A.G. Olsen, M. StefanonJ. M. Castro Cerón, J. P.U. Fynbo, S. T. Holland, C. Kouveliotou, H. Pedersen, N. R. Tanvir, S. E. Woosley

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


We present ground-based and Hubble Space Telescope optical observations of the X-ray flash (XRF) 020903, covering 300 days. The afterglow showed a very rapid rise in the first day, followed by a relatively slow decay in the next few days. There was a clear bump in the light curve after ∼25 days, accompanied by a drastic change in the spectral energy distribution. The light curve and the spectral energy distribution are naturally interpreted as describing the emergence and subsequent decay of a supernova (SN), similar to SN 1998bw. At peak luminosity, the SN is estimated to be 0.8 ± 0.1 mag fainter than SN 1998bw. This argues in favor of the existence of a SN associated with this XRF. A spectrum obtained 35 days after the burst shows emission lines from the host galaxy. We use this spectrum to put an upper limit on the oxygen abundance of the host at [O/H] < -0.6 dex. We also discuss a possible trend between the softness of several bursts and the early behavior of the optical afterglow, in the sense that XRFs and X-ray-rich gamma-ray bursts (GRBs) seem to have a plateau phase or even a rising light curve. This can be naturally explained in models in which XRFs are similar to GRBs but are seen off the jet axis.

Original languageEnglish (US)
Pages (from-to)284-291
Number of pages8
JournalAstrophysical Journal
Issue number1 I
StatePublished - May 20 2006


  • Gamma rays: bursts
  • Supernovae: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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