More than 13 years after the discovery of the first afterglows, the nature of dark gamma-ray bursts (GRB) has still eluded explanation: while each long-duration GRB typically has an X-ray afterglow, optical/NIR emission is only seen for 40-60% of those. Here we use the afterglow detection statistics of the systematic follow-up observations performed with GROND since mid-2007 in order to derive the fraction of "dark bursts". We find that the faint optical afterglow emission of "dark bursts" is due to a combination of two components: (i) moderate intrinsic extinction at moderate redshifts, and (ii) about 25% of bursts at redshift >5. © 2010 American Institute of Physics.
Greiner, J., Krühler, T., Klose, S., Afonso, P., Clemens, C., Filgas, R., et al. (2010). The nature of "dark" gamma-ray bursts. In Deciphering the ancient universe with gamma-ray bursts (pp.144-151). Kyoto : Nobuyuki Kawai, Shigehiro Nagataki [10.1063/1.3509253].
The nature of "dark" gamma-ray bursts
NARDINI, MARCO;
2010
Abstract
More than 13 years after the discovery of the first afterglows, the nature of dark gamma-ray bursts (GRB) has still eluded explanation: while each long-duration GRB typically has an X-ray afterglow, optical/NIR emission is only seen for 40-60% of those. Here we use the afterglow detection statistics of the systematic follow-up observations performed with GROND since mid-2007 in order to derive the fraction of "dark bursts". We find that the faint optical afterglow emission of "dark bursts" is due to a combination of two components: (i) moderate intrinsic extinction at moderate redshifts, and (ii) about 25% of bursts at redshift >5. © 2010 American Institute of Physics.
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