[论文解读] The second H.E.S.S. gamma-ray burst catalogue: 15 years of observations with the H.E.S.S. telescopes

A. Acharyya, F. ; https://orcid.org/0000-0003-1157-3915 Aharonian+145 more|arXiv (Cornell University)|Mar 23, 2026

Gamma-ray bursts and supernovae被引用 0

一句话总结

本论文展示了15年的H.E.S.S. GRB后续观测，未发现新的VHE探测，给出严格上限，并与Swift/Fermi人群进行比较，针对选定的爆发采用SSC建模。

ABSTRACT

Recent observational efforts using imaging atmospheric Cherenkov telescopes (IACTs) have led to firm detections of very-high-energy (VHE) signals from bright gamma-ray bursts (GRBs), often at moderate redshifts. This work presents 15 years of H.E.S.S. GRB observations and examines their implications through population comparisons and selected modelling cases. GRBs are a key science target of the High Energy Stereoscopic System (H.E.S.S.). With a low-energy threshold ($\lesssim$100 GeV) and rapid repointing capabilities, H.E.S.S. can begin follow-up observations within tens of seconds after a GRB trigger, covering the late prompt or early afterglow phases. We report GRB follow-up observations with H.E.S.S. from 2004 to 2019, which resulted in no significant VHE signals (aside from the detections of GRB~180720B and GRB~190829A). The resulting upper limits comprise the largest set available for GRBs at VHE. A subset of bursts with favourable conditions were selected for X-ray analysis and emission modelling. Population studies were performed to compare detected and non-detected GRBs. The results indicate that VHE-detected GRBs are not a distinct population, but tend to feature luminous X-ray emission and favourable redshift and observing conditions. This highlights the potential of next-generation IACTs such as the Cherenkov Telescope Array Observatory (CTAO), whose lower energy threshold will enhance the detection of fainter and more distant GRBs.

研究动机与目标

• 通过利用H.E.S.S.快速跟踪能力和低能阈值，推动对极高能（VHE）GRB的研究。
• 提供一个完整的15年H.E.S.S. GRB后续目录，并通过上限量化非探测情况。
• 探讨检测与非检测的GRB在X射线亮度、红移和观测条件上的对比。
• 使用XRT数据和H.E.S.S.上限，以单区同步自带散射（SSC）框架对选定GRB进行建模。

提出的方法

• 描述H.E.S.S.阵列及其对GRB的快速重新指向与跟进系统。
• 通过将2004–2019年的H.E.S.S.观测与Swift、Fermi/GBM、INTEGRAL、MAXI、HETE-2等目录进行相关分析，组建GRB样本。
• 在三种重建模式（立体 stere o、混合 hybrid、单端 mono）下进行两条独立分析链（Model++ with ParisCalibration；ImPACT with HAPCalibration）。
• 使用Rolke方法在幂律谱假设（指数-2.5、 loc为-5.0；非loc为-2.5）且部分通量无EBL修正下计算95%置信水平上限。
• 对theta^2分布进行堆叠分析，以评估定位较好爆发的集体VHE辐射。
• 对选定GRB，在XRT光谱拟合以获得本征吸收并用单区SSC框架建模SED。

Figure 1: Distribution of GRB follow-ups performed with H.E.S.S. between 2004 and 2019. A total of 89 GRBs are considered in the analysis, classified as either well-localised (loc, typically Swift /BAT alerts with position uncertainty $\lesssim$ 3 ′ ) or poorly localised (un-loc, mostly Fermi /GBM a

实验结果

研究问题

• RQ1 H.E.S.S.对2004–2019年观测的GRB是否检测到VHE伽马射线发射？

主要发现

• loc样本中未发现新的GRB探测；仅GRB 180720B和GRB 190829A 曾被H.E.S.S.探测过，另行讨论。
• 未探测得到的上限构成迄今为止最大的VHE GRB数据集。
• 对定位较好的GRB的堆叠分析在单端或立体配置中均未发现显著超额。
• 选定的、观测条件有利且X射线发射明亮的GRB可在XRT数据和H.E.S.S.上限的约束下，用单区SSC场景进行建模。
• 研究表明VHE探测的GRB往往具有亮丽的X射线发射和有利的红移/观测条件，这将为未来CTAO前景提供信息。

Figure 2: Significance distribution of the gamma-ray emission for the loc follow-ups. The distribution is shown in orange, and the fitted Gaussian is shown in blue. Each entry of the histogram corresponds to one GRB or cluster (see text for details).