Gamma-Ray Bursts and Optical Brightness: Insights from Swift Satellite
伽马射线暴与光学亮度:来自 Swift 卫星的洞见
During the examination of optical properties of gamma-ray bursts (GRBs) measured during the life of the Neil Gehrels Swift Observatory satellite, significant discoveries were made. While the satellite measures gamma, X-ray, and optical data simultaneously, in many cases, only an upper limit is established in the optical domain. Hence, survival analysis, a.k.a. dependability modelling, was necessary, serving as a tool for studying samples where some cases are bound only by the upper limit, as mentioned earlier. This method is used to analyse datasets that may have upper or lower bounds rather than precise observations, but nevertheless contain relevant information. It was previously established that the duration, gamma fluence, and peak flux all have a substantial effect on the optical brightness distribution, probably due to the energy of the beam from the GRB's central engine. However, after analysing more than 200 data points, we no longer see this association. This disagreement shows that the previously reported impact may not be as significant as previously derived, needing more research to better understand the underlying processes that determine the optical brightness in connection to gamma-ray properties.
展开 ▾对 155 个光学上限做截尾处理而非丢弃;用 Kaplan-Meier 和 Cox 回归在 437 个 GRB 样本中发现早期 gamma 参数与光学亮度无显著关联,挑战了之前小样本结论。
本文延续了用生存分析处理天文截尾数据的思路:早期对 GRB 宿主星系光学亮度的研究 Rácz+ 2014 已尝试该方法,而天文上限数据的统计处理可追溯到 Feigelson & Nelson 1985。此前分析曾提示 GRB 持续时间、伽马 fluence 和峰值流量会显著影响光学亮度分布,但本文在 437 个 Swift UVOT V 波段样本(含 155 个上限)中未重现这一关联,显示早期信号可能受样本规模或截尾处理差异影响。方法上,Kaplan-Meier 与 Cox 回归为不丢弃上限的检验提供了更稳健框架,未来可推广到 SVOM/THESEUS 等更大样本及多波段光学余辉。PL 与 CPL 谱型群体的比较同样未显示显著差异,提示瞬时 gamma 能谱参数与光学余辉亮度之间的关系比以往设想的更复杂。
预印本 2026-09-03 · 刊出 2025-03-06 · 收录 2026-09-04