Evidence for supernova-synthesized dust from the rising afterglow of GRB 071025 at z∼ 5
| Autor: | Y. Kakazu, Yuzuru Yoshii, Jochen Greiner, Takeo Minezaki, G. Grant Williams, Stefano Covino, A. Küpcü Yoldas, Nat Butler, Thomas Krühler, P. A. Price, Peter Milne, Dieter H. Hartmann, J. S. Bloom, Daniel A. Perley, P. Ferrero, W. T. Vestrand, C. R. Klein, Angelo Antonelli, L. Cowie, Jason X. Prochaska, P. R. Wozniak, P. M. J. Afonso, Adam N. Morgan, Adria C. Updike |
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| Rok vydání: | 2010 |
| Předmět: |
Physics
Astrophysics::High Energy Astrophysical Phenomena Extinction (astronomy) Astronomy and Astrophysics Quasar Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Light curve Galaxy Redshift Afterglow Space and Planetary Science Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics Gamma-ray burst Astrophysics::Galaxy Astrophysics Photometric redshift |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 406:2473-2487 |
| ISSN: | 0035-8711 |
| DOI: | 10.1111/j.1365-2966.2010.16772.x |
| Popis: | We present observations and analysis of the broadband 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 GRB trigger in the host frame and 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 Gamma_0 ~ 200. The red spectral energy distribution (even in regions not affected by the Lyman-alpha break) provides secure evidence of a large dust column. However, the inferred extinction curve shows a prominent flat component between 2000-3000 Angstroms in the rest-frame, inconsistent with any locally observed template but well-fit 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 Delta A_3000 < 0.54 mag after t = 50 s in the rest frame. Our observations provide evidence of a transition in dust properties at z~5, in agreement with studies of high-z quasars, and suggest that SN-formed dust continues to dominate the opacity of typical galaxies at this redshift. |
| Databáze: | OpenAIRE |
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