Limitation on the Viewing Angles of Long GRBs Based on Amati Relation
基于 Amati 关系对长伽马暴观测视角的限制
Fermi, Swift, and other observation satellites provided a dataset of 323 Long Gamma-Ray Bursts (LGRBs) with known redshift and well-defined spectral parameters spanning from February 1997 to September 2023. Among these, 123 GRBs (Gamma-Ray Bursts) observed by Fermi-GBM were selected to calibrate the relationship between the isotropic energy $E_{\rm{iso}}$ and the peak energy in the cosmological rest frame $E_{\rm{p,i}}$, known as the Amati relation. The analysis revealed that the $E_{\rm{iso}}$ of five LGRBs (GRB 980425, GRB 061210, GRB 070714B, GRB 071227, and GRB 080123A) significantly deviated from the Amati relation, suggesting that the jet of them may be off-axis to the line of sight. Utilizing the well-established $E_{\rm{p,i}}-\varGamma$ and $E_{\rm{p,i}}-E_{\rm{iso}}$ correlations, we estimated the viewing angles $\theta _{\rm{obs}}^{'}$ for these five LGRBs. The results show, $\theta^{'}_{\rm{obs}}=(0.42^{+0.29}_{-0.14})^\circ$ for GRB 980425, $\theta^{'}_{\rm{obs}}=(0.27^{+0.21}_{-0.10})^\circ$ for GRB 061210, $\theta^{'}_{\rm{obs}}=(0.10^{+0.09}_{-0.02})^\circ$ for GRB 070714B, $\theta^{'}_{\rm{obs}}=(0.13^{+0.09}_{-0.05})^\circ$ for GRB 071227, and $\theta^{'}_{\rm{obs}}=(0.12^{+0.14}_{-0.03})^\circ$ for GRB 080123A. Notably, all five $\theta _{\rm{obs}}^{'}$ values are small, with the maximum angle being $0.42^\circ$ for GRB 980425, the nearest long burst observed ($z=0.0085$). The results suggest that the majority of Long GRBs are likely detected on-axis, with only a small fraction of nearby Long GRBs being observed slightly outside the jet edge.
展开 ▾用 123 个 Fermi-GBM 长暴标定 Amati 关系,识别出 5 个显著偏离源,并首次给出它们视角的定量约束(最大仅 0.42°),支持长暴喷流多为在轴观测。
长伽马暴的 Amati 关系(E_iso–E_p,i)已被广泛用于研究喷流能量和宇宙学,而其偏离常被解释为观测视角偏离喷流轴。本文利用 123 个 Fermi-GBM 长暴重新标定这一关系,发现 5 个事件显著偏离,并通过 E_p,i–Γ 与 E_p,i–E_iso 经验相关估计出它们的视角均小于约 0.4°。这一结果支持长暴喷流张角较窄、多数事件被在轴探测的图景,但样本对邻近低能事件的偏向仍需注意。未来随着宽视场高能监视器、引力波及多信使观测的积累,对离轴长暴的比例和喷流角结构的限制有望进一步量化。
刊出 2026-01 · 收录 2026-08-20