Dust in the Wind: the Role of Recent Mass Loss in Long Gamma-Ray Bursts

摘要: We study the late-time ( days) X-ray afterglows of nearby () long gamma-ray bursts (GRBs) with Swift and identify a population explosions slowly decaying, super-soft (photon index ) emission that is inconsistent forward shock synchrotron radiation associated afterglow. These also show larger-than-average intrinsic absorption prompt γ-ray extremely duration s). The chance association these three rare properties (i.e., large , extreme duration) in same class statistically unlikely. associate turbulent mass-loss history progenitor star enriched shaped circumburst medium. natural connection between sources by suggesting X-rays originate from reprocessed material lost to environment stellar before exploding (either form dust echo or as long-lived GRB remnant), interaction explosion's shock/jet complex medium source emission. However, current observations do not allow us exclude possibility emitters peculiar progenitors radii only very dusty environments.