Photometric and Spectroscopic Observations of GRB 140629A

Li-Ping Xin, Shu-Qing Zhong, En-Wei Liang, Jing Wang, Hao Liu, Tian-Meng Zhang, Xiao-Li Huang, Hua-Li Li, Yu-Lei Qiu, Xu-Hui Han, Jian-Yan Wei
2018 Astrophysical Journal  
We present our optical photometric and spectroscopical observations of GRB 140629A. A redshift of z=2.275±0.043 is measured through the metal absorption lines in our spectroscopic data. Using our photometric data and multiple observational data observed with other telescopes, we show that its optical light curve is well interpreted with the standard forward shock models in the thin shell case. Its optical-X-ray afterglow spectrum is jointly fitted with a single power-law function, yielding a
more » ... ton index of -1.90± 0.05. The optical extinction and neutral hydrogen absorption of the GRB host galaxy are negligible. The fit to the light curve with the standard models shows that the ambient density is 60± 9 cm^-3 and the GRB radiating efficiency is as low as ∼ 0.24%, likely indicating a baryonic-dominated ejecta of this GRB. This burst agrees well with the L_ p, iso-E_p^'-Γ_0 relation, but confidently violates those empirical relations involving geometric corrections (or jet break time). This gives rise to an issue of possible selection effect on these relations since the jet opening angle of this GRB is extremely narrow (0.04 rad).
doi:10.3847/1538-4357/aabf3d fatcat:ci2zkokyzjfendfbn5qpcyxvqe