Optical light curve of GRB 121011A:a textbook for the onset of GRB afterglow in a mixture of ISM and wind-type medium  

作　　者：Li-Ping Xin Jian-Yan Wei Yu-Lei Qiu Jin-Song Deng Jing Wang Xu-Hui Han 

机构地区：[1]Key Laboratory of Space Astronomy and Technology,National Astronomical Observatories,Chinese Academy of Sciences

出　　处：《Research in Astronomy and Astrophysics》2016年第1期101-106,共6页天文和天体物理学研究（英文版）

基　　金：supported by the National Basic Research Program of China (973 program,2014CB845800);the National Natural Science Foundation of China (NSFC,Grant No.U1331202);the NSFC (Nos.11103036 and U1331101);supported by the NSFC (No.U1231115)

摘　　要：We report the optical observations of GRB 121011 A by the 0.8m TNT facility at Xinglong observatory, China. The light curve of the optical afterglow shows a smooth and featureless bump during the epoch of;30 s and;000 s with a rising index of 1.57 ± 0.28 before the break time of 539 ± 44 s, and a decaying index of about 1.29 ± 0.07 up to the end of our observations. Moreover, the X-ray light curve decays in a single power-law with a slope of about 1.51 ± 0.03 observed by XRT onboard Swift from 100 s to about 10 000 s after the burst trigger. The featureless optical light curve could be understood as an onset process under the external-shock model. The typical frequency has been below or near the optical one before the deceleration time, and the cooling frequency is located between the optical and X-ray wavelengths. The external medium density has a transition from a mixed stage of ISM and wind-type medium before the peak time to the ISM at the later phase. The joint-analysis of X-ray and optical light curves shows that the emissions from both frequencies are consistent with the prediction of the standard afterglow model without any energy injections, indicating that the central engine has stopped its activity and does not restart anymore after the prompt phase.We report the optical observations of GRB 121011 A by the 0.8m TNT facility at Xinglong observatory, China. The light curve of the optical afterglow shows a smooth and featureless bump during the epoch of ~130 s and ~5000 s with a rising index of 1.57 ± 0.28 before the break time of 539 ± 44 s, and a decaying index of about 1.29 ± 0.07 up to the end of our observations. Moreover, the X-ray light curve decays in a single power-law with a slope of about 1.51 ± 0.03 observed by XRT onboard Swift from 100 s to about 10 000 s after the burst trigger. The featureless optical light curve could be understood as an onset process under the external-shock model. The typical frequency has been below or near the optical one before the deceleration time, and the cooling frequency is located between the optical and X-ray wavelengths. The external medium density has a transition from a mixed stage of ISM and wind-type medium before the peak time to the ISM at the later phase. The joint-analysis of X-ray and optical light curves shows that the emissions from both frequencies are consistent with the prediction of the standard afterglow model without any energy injections, indicating that the central engine has stopped its activity and does not restart anymore after the prompt phase.

关 键 词：gamma-ray bursts -- stars： individual （GRB 121011A） 

分 类 号：P172.3[天文地球—天文学]