The X-ray afterglows of GRB 020813 and GRB 021004 with Chandra HETGS: Possible evidence for a supernova prior to GRB 020813

Nathaniel R. Butler, Herman L. Marshall, George R. Ricker, Roland K. Vanderspek, Peter G. Ford, Geoffrey B. Crew, Donald Q. Lamb, J. Garrett Jernigan

Research output: Contribution to journalArticle

54 Scopus citations

Abstract

We report on the detection of an emission line near 1.3 keV, which we associate with blueshifted hydrogen-like sulfur (S XVI), in a 76.8 ks Chandra HETGS spectrum of the afterglow of GRB 020813. The line is detected at 3.3 σ significance. We also find marginal evidence for a line possibly due to hydrogen-like silicon (Si XIV) with the same blueshift. A line from Fe is not detected, although a very low significance Ni feature may be present. A thermal model fits the data adequately, but a reflection model may provide a better fit. There is marginal evidence that the equivalent width of the S XVI line decreases as the burst fades. We infer from these results that a supernova likely occurred ≳2 months prior to the γ-ray burst. We find no discrete or variable spectral features in the Chandra HETGS spectrum of the GRB 021004 afterglow.

Original languageEnglish (US)
Pages (from-to)1010-1016
Number of pages7
JournalAstrophysical Journal
Volume597
Issue number2 I
DOIs
StatePublished - Nov 10 2003

Keywords

  • Gamma rays: Bursts
  • Supernovae: General
  • X-rays: General

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Butler, N. R., Marshall, H. L., Ricker, G. R., Vanderspek, R. K., Ford, P. G., Crew, G. B., Lamb, D. Q., & Garrett Jernigan, J. (2003). The X-ray afterglows of GRB 020813 and GRB 021004 with Chandra HETGS: Possible evidence for a supernova prior to GRB 020813. Astrophysical Journal, 597(2 I), 1010-1016. https://doi.org/10.1086/378511