ABSTRACT

We present and perform a detailed analysis of multiwavelength observations of GRB 140102A, an optical bright GRB with an observed reverse shock (RS) signature. Observations of this GRB were acquired with the BOOTES-4 robotic telescope, the Fermi, and the Swift missions. Time-resolved spectroscopy of the prompt emission shows that changes to the peak energy (E_p) tracks intensity and the low-energy spectral index seems to follow the intensity for the first episode, whereas this tracking behaviour is less clear during the second episode. The fit to the afterglow light curves shows that the early optical afterglow can be described with RS emission and is consistent with the thin shell scenario of the constant ambient medium. The late time afterglow decay is also consistent with the prediction of the external forward shock model. We determine the properties of the shocks, Lorentz factor, magnetization parameters, and ambient density of GRB 140102A, and compare these parameters with another 12 GRBs, consistent with having RS produced by thin shells in an interstellar medium like medium. The value of the magnetization parameter (R_B ≈ 18) indicates a moderately magnetized baryonic dominant jet composition for GRB 140102A. We also report the host galaxy photometric observations of GRB 140102A obtained with 10.4 m GTC, 3.5 m Calar Alto Astronomical Observatory, and 3.6 m Devasthal optical telescope and find the host (photo z = $2.8^{+0.7}_{-0.9}$) to be a high-mass, star-forming galaxy with a star formation rate of $20 \pm 10 {\rm ~M_{\odot }}\, \rm yr^{-1}$.

中文翻译：

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GRB 140102A：洞察快速光谱演化和早期光学余辉发射

摘要

我们对 GRB 140102A 的多波长观测进行了详细分析，这是一种具有观察到的反向激波 (RS) 特征的光学明亮 GRB。使用 BOOTES-4 机器人望远镜、费米和Swift任务获得了对这个 GRB 的观测。瞬发发射的时间分辨光谱显示峰值能量 ( E _p) 跟踪强度，低能量光谱指数似乎跟随第一集的强度，而这种跟踪行为在第二集期间不太清楚。对余辉光曲线的拟合表明，早期的光学余辉可以用 RS 发射来描述，并且与恒定环境介质的薄壳场景一致。后期余辉衰减也与外部前向激波模型的预测一致。我们确定了 GRB 140102A 的冲击特性、洛伦兹因子、磁化参数和环境密度，并将这些参数与另外 12 个 GRB 进行了比较，这与在星际介质等介质中由薄壳产生的 RS 一致。磁化参数值 ( R _B≈ 18) 表明 GRB 140102A 具有中等磁化的重子主导射流成分。我们还报告了用 10.4 m GTC、3.5 m Calar Alto 天文台和 3.6 m Devasthal 光学望远镜获得的 GRB 140102A 的宿主星系光度观测，并找到了宿主（照片z = $2.8^{+0.7}_{-0.9}$ ) 成为一个大质量的恒星形成星系，恒星形成率为 $20 \pm 10 {\rm ~M_{\odot }}\, \rm yr^{-1}$。