TY - JOUR
T1 - Exploring Dust Extinction at the Edge of Reionization
AU - Zafar, Tayyaba
AU - Watson, Darach Jafar
AU - Tanvir, N.R.
AU - Fynbo, Johan Peter Uldall
AU - Starling, R.L.C.
AU - Levan, A.J.
PY - 2011/7/1
Y1 - 2011/7/1
N2 - 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 > 6GRBs: GRB090423, 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 GRB050904 and GRB090423, with possible evidence for a low level of extinction in GRB080913. We compare the high redshift GRBs to a sample of lower redshift GRB extinctions and find a lack of even moderately extinguished events (AV 0.3) above z ≳ 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.
AB - 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 > 6GRBs: GRB090423, 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 GRB050904 and GRB090423, with possible evidence for a low level of extinction in GRB080913. We compare the high redshift GRBs to a sample of lower redshift GRB extinctions and find a lack of even moderately extinguished events (AV 0.3) above z ≳ 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.
U2 - 10.1088/0004-637X/735/1/2
DO - 10.1088/0004-637X/735/1/2
M3 - Journal article
SN - 0004-637X
VL - 735
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
ER -