GRB 090423 at z=8.23 - probing the extremely distant universe with GRBs

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• Klaas Wiersema, University of Leicester
• Wednesday 16 September 2009, 16:00-16:15
• Sackler Lecture Theatre, IoA.

If you have a question about this talk, please contact Alexander Blustin.

On the 23d of April 2009 a gamma-ray burst was detected by Swift, with unremarkable gamma-ray and X-ray properties. Our UKIRT rapid response programme for GRB follow-up was triggered by an automatic (eStar) system, which revealed a relatively bright source in J, H and K bands. Observations with Gemini-North were obtained soon after, revealing no source to very deep limits at wavelengths lower than ~1 micron, indicating a photometric redshift well above 7. We activated our VLT spectroscopy program for high redshift bursts, and acquired spectroscopy with ISAAC and SINFONI . The spectra give a spectroscopic redshift of 8.23, making GRB 090423 by some distance the most distant object known to date. I will show how the gamma-ray and X-ray optical properties gave little indication of such an extreme redshift, which highlights the need to follow-up every burst with Swift and groundbased facilities. I will discuss how we may be able to use the current and future X-ray, optical and radio facilities to use extremely high redshift GRBs to probe the reionisation and chemical enrichment history of the Universe.

This talk is part of the New Results in X-ray Astronomy 2009 series.

This talk is included in these lists:

• Combined External Astrophysics Talks DAMTP
• Cosmology, Astrophysics and General Relativity
• Institute of Astronomy One-day Meetings
• Institute of Astronomy Talk Lists
• New Results in X-ray Astronomy 2009
• Sackler Lecture Theatre, IoA

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