Dust Extinction of Gamma-ray Burst Host Galaxies: Identification of Two Classes?

Abstract

Dust in the host galaxies of gamma-ray bursts (GRBs) dims and reddens their afterglow spectra. Knowledge of the nature of this dust is crucial for correcting for extinction, providing clues to the nature of GRB progenitors, and probing the interstellar medium of high-redshift galaxies as well as the nature of cosmic dust when the universe was much younger and galaxies were much less evolved. The dust and extinction properties of GRB host galaxies are still poorly known. Unlike previous work, we derive in this Letter the extinction curves for 10 GRB host galaxies without a priori assumption of any specific extinction types (such as that of the Milky Way, or the Small/Large Magellanic Clouds). It is found that there appears to exist two different types of extinction curves: one is relatively flat and gray, the other displays a steeper dependence on inverse wavelength, closely resembling that of the Milky Way but with the 2175$\Angstrom$ feature removed.

15 pages, 3 figures. Substantially revised with the same arguments; accepted for publication in The Astrophysical Journal Letters

References in corpus (3)

• Long gamma-ray bursts and core-collapse supernovae have different environments
• The line-of-sight towards GRB 030429 at z = 2.66: Probing the matter at stellar, galactic and intergalactic scales
• Optical Photometry of GRB 021004: The First Month

Cited by in corpus (12)

• The Host Galaxies of Swift Dark Gamma-Ray Bursts: Observational Constraints on Highly Obscured and Very High-Redshift GRBs
• GRBs as Cosmological Probes - Cosmic Chemical Evolution
• Looking Into the Fireball: ROTSE-III and Swift Observations of Early GRB Afterglows
• The Remarkable Afterglow of GRB 061007: Implications for Optical Flashes and GRB Fireballs
• The nature of GRB-selected submillimeter galaxies: hot and young
• On Dust Extinction of Gamma-ray Burst Host Galaxies
• Extinction curves flattened by reverse shocks in supernovae
• Probing Cosmic Dust of the Early Universe through High-Redshift Gamma-Ray Bursts
• Determining the Dust Extinction of Gamma-ray Burst Host Galaxies: A Direct Method Based on Optical and X-ray Photometry
• X-ray Flashes or soft Gamma-ray Bursts? The case of the likely distant XRF 040912
• Astrophysics in 2006
• GRB 100614A and GRB 100615A: two extremely dark GRBs