GRB080319B:a high resolution spectroscopic view

摘要：

GRB080319B reached 5th optical mag during the burst．THanks to the VLT/UVES rapid response mode,weobserved its afterglow just 8m：30s after the GRB onset when R was～12．This allowed US to obtain the best signal-tonoise,high resolution spectrum of a GRB afterglow ever (S/N-50)．The spectrum is rich of absorption features belongingto the main system at z=0.937,divided in at least six components spanning a velocity range of 120 km/s．The observationscaught the absorbing gas in a highly excited state,producing the strongest Fell fine structure lines ever observed in a GRB．Afew hours later the optical depth of these lines was reduced by a factor of 4-20,and the optical/UV flux by a factor of～60．This proves that the excitation of the observed fine structure lines is due to“pumpingby the GRB UV pbotons．A comparisonof the observed ratio between the number of photons absorbed by the excited and ground state of the FelI suggests that thesix absorbers are～18-34 kpc from the GRB site,with component 1～2 times closer to the GRB site than components Ⅲto VI．This suggests a structured ISM in this galaxy complex．

关键词： Garoma-Ray Bursts

作者: V.D’Elia F.Fiore F.Nicastro Y.Krongold R.Perna

作者单位: INAF-OAR,Via di Frascati 33,00040 Monte Porzio,I Universidad Nacional Autonomica de Mexico,70-264,04510,Mexico DF JILA,CU Boulder 80309,USA

会议类型: 国际会议

会议名称: 2008 NanJing Gamma-Ray Burst Conference(2008年伽马暴国际研讨会)

会议地点: 南京

会议语种:英文

页码: 255-258

在线出版日期: 2008-06-23（万方平台首次上网日期，不代表论文的发表时间）