The extreme, red afterglow of GRB 060923A: distance or dust?
Abstract
Gamma-ray bursts (GRBs) are powerful probes of the early Universe, but locating and identifying very distant GRBs remain challenging. We report here the discovery of the K-band afterglow of Swift GRB 060923A, imaged within the first hour post-burst, and the faintest so far found. It was not detected in any bluer bands to deep limits, making it a candidate very high-z burst (z >~ 11). However, our later-time optical imaging and spectroscopy reveal a faint galaxy coincident with the GRB position which, if it is the host, implies a more moderate redshift (most likely z <~ 2.8) and therefore that dust is the likely cause of the very red-afterglow colour. This being the case, it is one of the few instances so far found of a GRB afterglow with high-dust extinction.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2008
- DOI:
- 10.1111/j.1365-2966.2008.13496.x
- arXiv:
- arXiv:0803.4100
- Bibcode:
- 2008MNRAS.388.1743T
- Keywords:
-
- galaxies: high-redshift;
- gamma-rays: bursts;
- Astrophysics
- E-Print:
- Submitted to MNRAS (revised in light of referee's comments)