Long-term continuous energy injection in the afterglow of GRB 060729  

作　　者：Ming Xu Yong-Feng Huang Tan Lu 

机构地区：[1]Department of Astronomy, Nanjing University, Nanjing 210093, China [2]Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China

出　　处：《Research in Astronomy and Astrophysics》2009年第12期1317-1323,共7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 (Grant Nos.10625313 and 10473023);the National Basic Research Program of China (973 Program,Grant No.2009CB824800)

摘　　要：A long plateau phase and an amazing level of brightness have been observed in the X-ray afterglow of GRB 060729. This peculiar light curve is likely due to longterm energy injection in external shock. Here, we present a detailed numerical study of the energy injection process of magnetic dipole radiation from a strongly magnetized millisecond pulsar and model the multi-band afterglow observations. It is found that this model can successfully explain the long plateaus in the observed X-ray and optical afterglow light curves. The sharp break following the plateaus could be due to the rapid decline of the emission power of the central pulsar. At an even later time （～ 5×10^6 s）, an obvious jet break appears, which implies a relatively large half opening angle of θ ～ 0.3 for the GRB ejecta. Due to the energy injection, the Lorentz factor of the outflow is still larger than two even at 10^7 s after the GRB trigger, making the X-ray afterglow of this burst detectable by Chandra even 642 d after the burst.A long plateau phase and an amazing level of brightness have been observed in the X-ray afterglow of GRB 060729. This peculiar light curve is likely due to longterm energy injection in external shock. Here, we present a detailed numerical study of the energy injection process of magnetic dipole radiation from a strongly magnetized millisecond pulsar and model the multi-band afterglow observations. It is found that this model can successfully explain the long plateaus in the observed X-ray and optical afterglow light curves. The sharp break following the plateaus could be due to the rapid decline of the emission power of the central pulsar. At an even later time （～ 5×10^6 s）, an obvious jet break appears, which implies a relatively large half opening angle of θ ～ 0.3 for the GRB ejecta. Due to the energy injection, the Lorentz factor of the outflow is still larger than two even at 10^7 s after the GRB trigger, making the X-ray afterglow of this burst detectable by Chandra even 642 d after the burst.

关 键 词：gamma rays： bursts -- ISM： jets and outflows 

分 类 号：P172.3[天文地球—天文学] TN432[电子电信—微电子学与固体电子学]