On Dust Extinction of Gamma-ray Burst Host Galaxies

Abstract

Although it is well recognized that gamma-ray burst (GRB) afterglows are obscured and reddened by dust in their host galaxies, the wavelength-dependence and quantity of dust extinction are still poorly known. Current studies on this mostly rely on fitting the afterglow spectral energy distributions (SEDs) with template extinction models. The inferred extinction (both quantity and wavelength-dependence) and dust-to-gas ratios are often in disagreement with that obtained from dust depletion and X-ray spectroscopy studies. We argue that this discrepancy could result from the prior assumption of a template extinction law. We propose an analytical formula to approximate the GRB host extinction law. With the template extinction laws self-contained, and the capability of revealing extinction laws differing from the conventional ones, it is shown that this is a powerful approach in modeling the afterglow SEDs to derive GRB host extinction.

9 pages, 4 figures; The Astrophysical Journal, in press (2008 Oct 1 issue)

References in corpus (10)

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Cited by in corpus (6)

• The Host Galaxies of Swift Dark Gamma-Ray Bursts: Observational Constraints on Highly Obscured and Very High-Redshift GRBs
• Probing Cosmic Dust of the Early Universe through High-Redshift Gamma-Ray Bursts
• Statistical studies of optically dark gamma-ray bursts in the Swift era
• Gamma-ray burst afterglows : luminosity clustering at infrared wavelengths?
• The nature of Long-GRB host galaxies from chemical abundances
• GRB 100614A and GRB 100615A: two extremely dark GRBs