The spectroscopic variability of GRB 021004

  • T. Matheson
  • , P. M. Garnavich
  • , C. Foltz
  • , S. West
  • , G. Williams
  • , E. Falco
  • , M. L. Calkins
  • , F. J. Castander
  • , E. Gawiser
  • , S. Jha
  • , D. Bersier
  • , K. Z. Stanek

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

We present spectra of the optical transient (OT) associated with GRB 021004. The spectra show a blue continuum with superposed absorption features and one emission line. We confirm two intervening metal-line systems at z = 1.380 and z = 1.602 and one very strong absorption system at a redshift of z = 2.323. Lyα emission is also seen at this redshift. While the spectrum of the OT overall cannot be simply described with a power law, the spectral index over the range 5500-8850 Å is steep, Fv ∝ v- 0.93±0.03. Comparison of spectra from multiple epochs shows a distinct color evolution with the OT becoming redder with time over the first 3 days. This is the first clear example of color change in an OT detected spectroscopically.

Original languageEnglish (US)
Pages (from-to)L5-L9
JournalAstrophysical Journal
Volume582
Issue number1 II
DOIs
StatePublished - Jan 1 2003

Keywords

  • Galaxies: ISM
  • Galaxies: distances and redshifts
  • Gamma rays: bursts
  • Ultraviolet: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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