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Perley, DA, Bloom, JS, Butler, NR, Pollack, LK, Holtzman, J, Blake, CH, Kocevski, D, Vestrand, WT, Li, W, Foley, RJ, Bellm, E, Chen, HW, Prochaska, JX, Starr, D, Filippenko, AV, Falco, EE, Szentgyorgyi, AH, Wren, J, Wozniak, PR, White, R and Pergande, J (2008) The troublesome broadband evolution of GRB 061126: Does a gray burst imply gray dust? The Astrophysical Journal, 672 (1). pp. 449-464. ISSN 1538-4357
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Abstract
We report on observations of a gamma-ray burst (GRB 061126) with an extremely bright (R ≈ 12 mag at peak) early-time optical afterglow. The optical afterglow is already fading as a power law 22 s after the trigger, with no detectable prompt contribution in our first exposure, which was coincident with a large prompt-emission gamma-ray pulse. The optical-infrared photometric SED is an excellent fit to a power law, but it exhibits a moderate red-to-blue evolution in the spectral index at about 500 s after the burst. This color change is contemporaneous with a switch from a relatively fast decay to slower decay. The rapidly decaying early afterglow is broadly consistent with synchrotron emission from a reverse shock, but a bright forward-shock component predicted by the intermediate- to late-time X-ray observations under the assumptions of standard afterglow models is not observed. Indeed, despite its remarkable early-time brightness, this burst would qualify as a dark burst at later times on the basis of its nearly flat optical-to-X-ray spectral index. Our photometric SED provides no evidence of host galaxy extinction, requiring either large quantities of gray dust in the host system (at redshift 1.1588 ± 0.0006, based on our late-time Keck spectroscopy) or separate physical origins for the X-ray and optical afterglows. © 2008. The American Astronomical Society. All rights reserved.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 0201 Astronomical And Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (Incl. Structural) |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics Q Science > QD Chemistry |
| Divisions: | Astrophysics Research Institute |
| Publisher: | American Astronomical Society |
| Date Deposited: | 23 May 2017 10:21 |
| Last Modified: | 20 Apr 2022 09:12 |
| DOI or ID number: | 10.1086/523929 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/6507 |
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