Evidence for supernova-synthesized dust from the rising afterglow of GRB 071025 at z ∼ 5

Daniel A. Perley, J. S. Bloom, C. R. Klein, S. Covino, T. Minezaki, P. Woźniak, W. T. Vestrand, George G Williams, P. Milne, N. R. Butler, A. C. Updike, T. Krühler, P. Afonso, A. Antonelli, L. Cowie, P. Ferrero, J. Greiner, D. H. Hartmann, Y. Kakazu, A. Küpcü YoldaşA. N. Morgan, P. A. Price, J. X. Prochaska, Y. Yoshii

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

We present observations and analysis of the broad-band afterglow of Swift GRB 071025. Using optical and infrared (RIYJHK) photometry, we derive a photometric redshift of 4.4 < z < 5.2; at this redshift our simultaneous multicolour observations begin at ∼30 s after the gamma-ray burst trigger in the host frame, during the initial rising phase of the afterglow. We associate the light-curve peak at ∼580 s in the observer frame with the formation of the forward shock, giving an estimate of the initial Lorentz factor Γ0 ∼ 200. The red spectral energy distribution (even in regions not affected by the Lyman α break) provides secure evidence of a large dust column. However, the inferred extinction curve shows a prominent flat component between 2000 and 3000 Å in the rest frame, inconsistent with any locally observed template but well fitted by models of dust formed by supernovae. Time-dependent fits to the extinction profile reveal no evidence of dust destruction and limit the decrease in the extinction column to ΔA3000 < 0.54 mag after t = 50 s in the rest frame. Together with studies of high-z quasars, our observations suggest a transition in dust properties in the early Universe, possibly associated with a transition between supernova-dominated and asymptotic giant branch-dominated modes of dust production.

Original languageEnglish (US)
Pages (from-to)2473-2487
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Volume406
Issue number4
DOIs
StatePublished - Aug 2010

Keywords

  • Dust, extinction
  • Gamma-ray burst: general
  • Gamma-ray burst: individual: 071025

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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