Delayed onset and fast rise of prompt optical-UV emission from gamma-ray bursts in molecular clouds  

作　　者：Xiao-Hong Cui Zhuo Li Li-Ping Xin 

机构地区：[1]National Astronomical Observatories,Chinese Academy of Sciences [2]Department of Astronomy,Peking University [3]Kavli Institute for Astronomy and Astrophysics,Peking University

出　　处：《Research in Astronomy and Astrophysics》2013年第1期57-70,共14页天文和天体物理学研究（英文版）

基　　金：Supported by the National Natural Science Foundation of China;supported by the National Basic Research Programof China (973 Program,2009CB824800);the China Postdoctoral Science Foundation funded project(No. 20110490590);the National Natural Science Foundation of China (Grant No. 111030262);the Foundation for the Authors of National Excellent Doctoral Dissertations of China

摘　　要：Observations imply that long ＂y-ray bursts （GRBs） originate from the explo- sions of massive stars, therefore they may occur in the molecular clouds where their progenitors were born. We show that the prompt optical-UV emission from GRBs may be delayed due to dust extinction, which can explain the observed optical delayed on- set and fast rise in GRB 080319B well. The density and the size of the molecular cloud around GRB 080319B are roughly constrained to be ~ 103 cm-z and ~ 8 pc, respectively. We also investigate other GRBs with prompt optical-UV data, and find similar values of the densities and sizes of the local molecular clouds. Future obser- vations of prompt optical-UV emission from GRBs on a timescale of subseconds, e.g. by UFFO-Pathfinder and SVOM-GWAC, will provide more evidence and probes of the local environments of GRBs.Observations imply that long ＂y-ray bursts （GRBs） originate from the explo- sions of massive stars, therefore they may occur in the molecular clouds where their progenitors were born. We show that the prompt optical-UV emission from GRBs may be delayed due to dust extinction, which can explain the observed optical delayed on- set and fast rise in GRB 080319B well. The density and the size of the molecular cloud around GRB 080319B are roughly constrained to be ~ 103 cm-z and ~ 8 pc, respectively. We also investigate other GRBs with prompt optical-UV data, and find similar values of the densities and sizes of the local molecular clouds. Future obser- vations of prompt optical-UV emission from GRBs on a timescale of subseconds, e.g. by UFFO-Pathfinder and SVOM-GWAC, will provide more evidence and probes of the local environments of GRBs.

关 键 词：radiation mechanisms： non-thermal -- gamma-rays： bursts -- dust： ex-tinction 

分 类 号：P159[天文地球—天文学]