The updated Bulk Lorentz Factors of Gamma-Ray Burst X-Ray Flares  

作　　者：Shao-Qiang Xi Shuang-Xi Yi Yuan-Chuan Zou Fa-Yin Wang 

机构地区：[1]College of Physics and Engineering, Qufu Normal University, Qufu 273165, China [2]School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China [3]School of Astronomy and Space Science, Nanjing University, Nanjing 210093, China [4]Key Laboratory of Modem Astronomy and Astrophysics (Nanjing University), Nanjing 210093, China

出　　处：《Research in Astronomy and Astrophysics》2017年第6期37-46,共10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,Grant No.2014CB845800);China Postdoctoral Science Foundation(Grant No.2017M612233);the National Natural Science Foundation of China(Grant Nos.11422325 and 11373022);the Excellent Youth Foundation of Jiangsu Province(BK 20140016)

摘　　要：X-ray flares are the most common phenomena in the afterglow phase of gamma-ray bursts （GRBs） in the Swift era, and are known as a canonical component in X-ray afterglows. In this work, we constrain the Lorentz factor of X-ray flares with an updated sample. We extensively search for X-ray light curves showing flare and jet break simultaneously. A smooth broken power law function is used to fit the jet breaks in 11 GRBs. We also use a smooth broken power law function to fit the profile of X-ray flares, and the total number of the flares is 20. We obtain the lower and upper limits of Lorentz factor （Гx） with the timescale, half-opening angle and mean luminosity of the X-ray flares for interstellar medium （ISM） and wind cases. The lower limits on Px range from tens to a few hundred, and the upper limits are mainly about a few hundred. We also apply the limited Lorentz factor to test correlations of Г0 - γ,iso and Г0 - Lγ,iso for GRBs, and find X-ray flares in the ISM case are much more consistent with those of prompt emission than the wind case in a statistical sense for both correlations. X-ray flares are almost consistent with the trend in the correlations of Г0 - Eγ,iso（Lγ,iso） for prompt GRBs, indicating X-ray flares and prompt bursts may have the same physical origin.X-ray flares are the most common phenomena in the afterglow phase of gamma-ray bursts （GRBs） in the Swift era, and are known as a canonical component in X-ray afterglows. In this work, we constrain the Lorentz factor of X-ray flares with an updated sample. We extensively search for X-ray light curves showing flare and jet break simultaneously. A smooth broken power law function is used to fit the jet breaks in 11 GRBs. We also use a smooth broken power law function to fit the profile of X-ray flares, and the total number of the flares is 20. We obtain the lower and upper limits of Lorentz factor （Гx） with the timescale, half-opening angle and mean luminosity of the X-ray flares for interstellar medium （ISM） and wind cases. The lower limits on Px range from tens to a few hundred, and the upper limits are mainly about a few hundred. We also apply the limited Lorentz factor to test correlations of Г0 - γ,iso and Г0 - Lγ,iso for GRBs, and find X-ray flares in the ISM case are much more consistent with those of prompt emission than the wind case in a statistical sense for both correlations. X-ray flares are almost consistent with the trend in the correlations of Г0 - Eγ,iso（Lγ,iso） for prompt GRBs, indicating X-ray flares and prompt bursts may have the same physical origin.

关 键 词：gamma ray bursts -radiation mechanism： non-thermal 

分 类 号：P172.2[天文地球—天文学]