Abstract

We have carried out a systematic analysis of the light curves of gamma-ray bursts (GRBs) detected in the SPI-ACS experiment onboard the INTEGRAL observatory to search for extended emission. The emission occasionally recorded after the prompt active phase of a GRB in the form of an emission that is longer than the active phase and less intense is called the extended one. Out of the 739 brightest GRBs recorded from 2002 to 2017, extended emission has been detected in \({\sim}20\%\) of the individual light curves; its maximum duration reaches 10 000 s. Two different types of extended emission have been revealed. One of them is an additional component of the light curve, which is described by a power law (PL) with an index of \(\alpha\sim{-}1\) close to the PL index of the afterglow in the optical and X-ray bands. The second type can be described by a steeper PL decay of the light curve typical of the active burst phase. Extended emission has also been found in the combined light curve of long GRBs in the individual curves of which no extended emission has been detected. The PL index of the extended emission in the combined light curve is \(\alpha\sim{-}2.4\). It is most likely associated with the superposition of light curves at the active phase; its total duration is 800 s.

中文翻译：

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在 SPI-ACS/INTEGRAL 实验中探测到的宇宙伽马射线爆发的扩展发射

摘要

我们对 INTEGRAL 天文台上的 SPI-ACS 实验中检测到的伽马射线暴 (GRB) 的光变曲线进行了系统分析，以寻找扩展发射。在 GRB 的快速活动阶段之后偶尔记录的以比活动阶段更长但强度较小的发射形式的发射称为扩展发射。在 2002 年至 2017 年记录的 739 个最亮的 GRB 中，在单个光变曲线的\({\sim}20\%\)中检测到了扩展发射；其最长持续时间达到 10 000 秒。已经揭示了两种不同类型的扩展发射。其中之一是光变曲线的附加分量，由指数为\(\alpha\sim{-}1\)的幂律 (PL) 描述接近于光学和 X 射线波段中余辉的 PL 指数。第二种类型可以通过活跃突发阶段典型的光曲线的更陡峭的 PL 衰减来描述。在长 GRB 的组合光曲线中也发现了扩展发射，而在单个曲线中没有检测到扩展发射。组合光曲线中扩展发射的 PL 指数为\(\alpha\sim{-}2.4\)。最有可能与活动阶段光变曲线的叠加有关；其总持续时间为 800 秒。