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Extinction properties of the X-ray bright/optically faintafterglow of GRB 020405
Ist Teil von
Astronomy and astrophysics (Berlin), 2005-10, Vol.441 (1), p.83-88
Ort / Verlag
EDP Sciences
Erscheinungsjahr
2005
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
We present an optical-to-X-ray spectral analysis of the afterglow of GRB 020405. The optical spectral energy distribution not corrected for the extragalactic extinction is significantly below the X-ray extrapolation of the single powerlaw spectral model suggested by multiwavelength studies. We investigate whether considerable extinction could explain the observed spectral “mismatch” by testing several types of extinction curves. For the first time we test extinction curves computed with time-dependent numerical simulations of dust grains destruction by the burst radiation. We find that an extinction law weakly dependent on wavelength can reconcile the unabsorbed optical and X-ray data with the expected synchrotron spectrum. A gray extinction law can be provided by a dust grain size distribution biased toward large grains.