Ultra-long Gamma-Ray Bursts (ulGRBs) are Gamma-Ray Bursts (GRBs) with an unusually long emission in X and gamma rays, reaching durations of thousands of seconds. They could form a specific class of high-energy transient events, whose origin is still under discussion. The current sample of known ulGRBs consists of a few tens of events which have been detected so far by the Burst Alert Telescope (BAT) aboard the Neil Gehrels Swift Observatory and some other instruments. The SVOM mission which is scheduled to begin operations after 2021 could help to detect and observe more ulGRBs thanks to its soft gamma-ray telescope ECLAIRs. After an introduction on ulGRBs and the SVOM mission, we present the results of our simulations on the capabilities of ECLAIRs to detect ulGRBs. First we use the sample of ulGRBs detected by Swift/BAT and simulate these events through a model of the instrument and the prototype trigger software that will be implemented onboard ECLAIRs. Then we present a study of the ECLAIRs capabilities to detect a synthetic population of ulGRBs built by transporting the ulGRBs detected by Swift/BAT to higher redshifts. Finally we give an estimate of the ulGRB rate expected to be detected by ECLAIRs and show that ECLAIRs can detect at least as much ulGRBs as BAT.

中文翻译：

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使用 SVOM/ECLAIR 进行超长伽马射线爆发检测

超长伽马射线暴 (ulGRB) 是具有异常长的 X 射线和伽马射线发射的伽马射线暴 (GRB)，持续时间可达数千秒。它们可以形成特定类别的高能瞬态事件，其起源仍在讨论中。当前已知 ulGRB 的样本由 Neil Gehrels Swift 天文台上的突发警报望远镜 (BAT) 和其他一些仪器迄今为止探测到的几十个事件组成。由于其软伽马射线望远镜 ECLAIR，计划于 2021 年之后开始运行的 SVOM 任务可以帮助探测和观察更多 ulGRB。在介绍了 ulGRB 和 SVOM 任务之后，我们展示了我们对 ECLAIRs 检测 ulGRB 能力的模拟结果。首先，我们使用 Swift/BAT 检测到的 ulGRB 样本，并通过仪器模型和将在 ECLAIR 上实现的原型触发软件来模拟这些事件。然后，我们介绍了 ECLAIRs 检测合成 ulGRB 群体的能力的研究，该群体是通过将 Swift/BAT 检测到的 ulGRB 传输到更高的红移而构建的。最后，我们估计了 ECLAIR 预期检测到的 ulGRB 率，并表明 ECLAIR 可以检测到至少与 BAT 一样多的 ulGRB。