Simon de Wet, Tanmoy Laskar, Paul J. Groot, Rodolfo Barniol Duran, Edo Berger, Shivani Bhandari, Tarraneh Eftekhari, Cristiano Guidorzi, Shiho Kobayashi, Daniel A. Perley, Re’em Sari and Genevieve Schroeder
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引用次数: 0
摘要
我们展示了对明亮的长伽马射线暴 GRB 210702A 的 X 射线到射频观测结果。我们的阿塔卡马大型毫米波/亚毫米波阵列 97.5 GHz 观测结果表明,从爆发后 8.2 天开始,亮度出现了显著的回升,回升系数≈2,并在 18.1 天达到峰值亮度,然后再次下降。这是在毫米余辉光曲线中首次看到的这种再增亮现象。恒星风环流介质中的标准前向冲击模型可以解释回亮之前的大部分 X 射线、光学和毫米波观测结果,但对自吸收射电辐射的预测明显偏高,而且无法解释毫米波回亮现象。我们对毫米波重亮的可能解释进行了研究,发现能量注入或晚期壳碰撞产生的反向冲击是可信的原因。与其他爆发类似,我们的射电数据可能需要热电子群或结构喷流等其他方案来解释。我们的观测结果表明,毫米波长的光变曲线可以表现出光学和 X 射线余辉光变曲线中常见的一些丰富特征,这促使我们对 GRB 余辉进行进一步的毫米波长研究。
We present X-ray to radio frequency observations of the bright long gamma-ray burst GRB 210702A. Our Atacama Large Millimeter/submillimeter Array 97.5 GHz observations show a significant rebrightening by a factor of ≈2 beginning at 8.2 days post-burst and rising to peak brightness at 18.1 days before declining again. This is the first such rebrightening seen in a millimeter afterglow light curve. A standard forward shock model in a stellar wind circumburst medium can explain most of our X-ray, optical, and millimeter observations prior to the rebrightening, but significantly overpredicts the self-absorbed radio emission, and cannot explain the millimeter rebrightening. We investigate possible explanations for the millimeter rebrightening, and find that energy injection or a reverse shock from a late-time shell collision are plausible causes. Similar to other bursts, our radio data may require alternative scenarios such as a thermal electron population or a structured jet to explain the data. Our observations demonstrate that millimeter light curves can exhibit some of the rich features more commonly seen in optical and X-ray afterglow light curves, motivating further millimeter wavelength studies of GRB afterglows.