Exploring dust extinction at the edge of reionization
Zafar, Tayyaba, Watson, Darach J., Tanvir, Nial R., Fynbo, Johan P. U., Starling, Rhaana L. C. and Levan, A. J.. (2011) Exploring dust extinction at the edge of reionization. The Astrophysical Journal, Vol.735 (No.1). article no. 2. ISSN 0004-637XFull text not available from this repository.
Official URL: http://dx.doi.org/10.1088/0004-637X/735/1/2
The brightness of gamma-ray burst (GRB) afterglows and their occurrence in young, blue galaxies make them excellent probes to study star-forming regions in the distant universe. We here elucidate dust extinction properties in the early universe through the analysis of the afterglows of all known z > 6 GRBs: GRB 090423, 080913, and 050904, at z = 8.2, 6.69, and 6.295, respectively. We gather all available optical and near-infrared photometry, spectroscopy, and X-ray data to construct spectral energy distributions (SEDs) at multiple epochs. We then fit the SEDs at all epochs with a dust-attenuated power law or broken power law. We find no evidence for dust extinction in GRB 050904 and GRB 090423, with possible evidence for a low level of extinction in GRB 080913. We compare the high redshift GRBs to a sample of lower redshift GRB extinctions and find a lack of even moderately extinguished events (A(V) similar to 0.3) above z greater than or similar to 4. In spite of the biased selection and small number statistics, this result hints at a decrease in dust content in star-forming environments at high redshifts.
|Item Type:||Journal Article|
|Subjects:||Q Science > QB Astronomy|
|Divisions:||Faculty of Science > Physics|
|Library of Congress Subject Headings (LCSH):||Ionization, Cosmic dust, Early stars, Gamma ray bursts|
|Journal or Publication Title:||The Astrophysical Journal|
|Publisher:||Institute of Physics Publishing, Inc.|
|Page Range:||article no. 2|
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