Near-infrared colors of gamma-ray burst afterglows and cosmic reionization history

Akio K. Indue*, Ryo Yamazaki, Takashi Nakamura

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


We discuss a way to study the cosmic reionization history using near-infrared (NIR) observations of the afterglows of high-redshift (5 ≲ z ≲ 25) gamma-ray bursts (GRBs) that will be detected by the Swift satellite. In principle, details of the cosmic reionization history should be imprinted in the NIR spectra of GRB afterglows. However, spectroscopy with a space telescope is required to obtain such information for very high redshifts (z ≳ 15) unless the neutral fraction of the high-z universe is less than 10-6. The broadband photometry has higher sensitivity than the spectroscopy, so that NIR photometric follow-up of GRB afterglows is very promising for examining cosmic reionization history. A few minutes exposure with a 8 m class ground-based telescope of the afterglows of the high-z GRBs will reveal how many times reionization occurred in the universe.

Original languageEnglish
Pages (from-to)644-653
Number of pages10
JournalAstrophysical Journal
Issue number2 I
Publication statusPublished - 2004 Feb 1
Externally publishedYes


  • Cosmology: observations
  • Gamma rays: bursts
  • Intergalactic medium
  • Radiative transfer
  • Techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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