Title: Delayed Onset of High-Energy Emissions in Leptonic and Hadronic Models of Gamma-Ray Bursts Show Chinese title

Title: 伽马射线暴 leptonic 和 hadronic 模型中高能辐射的延迟出现

Abstract: The temporal--spectral evolution of the prompt emission of gamma-ray bursts (GRBs) is simulated numerically for both leptonic and hadronic models. For weak enough magnetic fields, leptonic models can reproduce the few seconds delay of the onset of GeV photon emission observed by Fermi-LAT, due to the slow growth of the target photon field for inverse Compton scattering. However, even for stronger magnetic fields, the GeV delay can be explained with hadronic models, due to the long acceleration timescale of protons and the continuous photopion production after the end of the particle injection. While the FWHMs of the MeV and GeV lightcurves are almost the same in one-zone leptonic models, the FWHM of the 1--30 GeV lightcurves in hadronic models are significantly wider than those of the 0.1--1 MeV lightcurves. The amount of the GeV delay depends on the importance of the Klein--Nishina effect in both the leptonic and hadronic models. In our examples of hadronic models the energies of the escaped neutrons are comparable to the gamma-ray energy, although their contribution to the ultra high-energy cosmic rays is still subdominant. The resulting neutrino spectra are hard enough to avoid the flux limit constraint from IceCube. The delay of the neutrino emission onset is up to several times longer than the corresponding delay of the GeV photon emission onset. The quantitative differences in the lightcurves for various models may be further tested with future atmospheric Cherenkov telescopes whose effective area is larger than that of Fermi-LAT, such as CTA. Show Chinese abstract

Abstract: 伽马射线暴（GRBs）瞬时辐射的时间—光谱演化对于轻子模型和强子模型均被数值模拟。 对于足够弱的磁场，由于逆康普顿散射靶向光场增长缓慢，轻子模型可以重现费米-LAT观测到的GeV光子辐射起始的几秒延迟现象。 然而，即便是在更强的磁场下，强子模型也可以通过质子长加速时间尺度以及粒子注入结束后持续的光致π介子产生来解释GeV延迟现象。 在一区轻子模型中，MeV和GeV光变曲线的FWHMs几乎相同，而在强子模型中，1–30 GeV光变曲线的FWHM显著宽于0.1–1 MeV光变曲线。 GeV延迟量取决于轻子和强子模型中Klein-Nishina效应的重要性。 在我们的强子模型例子中，逃逸中子的能量与伽马射线能量相当，尽管它们对超高能宇宙射线的贡献仍然次要。 由此产生的中微子谱足够硬，可避免来自冰立方中微子天文台的流量限制约束。 中微子发射起始的延迟时间最多比相应的GeV光子发射起始的延迟时间长数倍。 各种模型光变曲线的数量级差异可能可通过未来的大气切伦科夫望远镜进一步验证，其有效面积大于费米-LAT，例如CTA。