AI 中文总结
本研究通过三种源演化模型拟合观测数据，发现本地窄喷流GRB种群可解释最高能UHECR通量，且不违反多信使约束，其重子加载因子约为10。
AI 中文摘要
伽马射线暴（GRB）长期以来被认为是超高能宇宙线（UHECR）的候选来源，原因在于其巨大的能量释放和相对论性外流。对GRB 221009A的多TeV伽马射线的探测及其稀有性，重新唤起了人们对这一关联的兴趣，并促使人们考虑在本地宇宙中存在额外的窄喷流长GRB种群。我们研究这种本地窄喷流种群是否能对观测到的弥散UHECR能谱做出贡献，同时还研究了相关的宇宙成因中微子和级联伽马射线辐射，以评估该场景的多信使可行性。我们使用三种源演化模型拟合观测到的UHECR能谱和质量组成数据：均匀共动源发射率模型、追踪恒星形成率（SFR）的标准喷流GRB种群模型，以及追踪SFR的标准+窄喷流GRB种群模型。我们传播混合组成的UHECR注入，并计算宇宙成因中微子和级联伽马射线通量。标准+窄喷流模型能够拟合观测到的UHECR能谱和组成，其中最高能通量由局限于z≤z_{max,*}≃0.36的窄喷流种群主导。这种低红移主导地位与标准喷流GRB种群相比降低了宇宙成因中微子通量。对于窄喷流GRB种群，拟合结果表明重子加载因子ξ_{CR}^{nj}≃10。因此，这种局部增强的长GRB种群可以解释最高能UHECR通量，而不会违反当前的多信使约束。未来的UHE搜索可以通过相关的宇宙成因通量进一步探测该场景。
英文摘要
Gamma-ray bursts (GRBs) have long been considered candidate sources of ultrahigh-energy cosmic rays (UHECRs) due to their large energy release and relativistic outflows. The detection of multi-TeV $γ$-rays from GRB~221009A and its rarity have renewed interest in this connection and motivate considering an additional narrow-jet long GRB population in the local Universe. We investigate whether such a local narrow-jet population can contribute to the observed diffuse UHECR energy spectrum. We also examine the associated cosmogenic neutrino and cascade $γ$-ray emissions to assess the multimessenger viability of this scenario. We fit the observed UHECR spectrum and mass composition data using three source-evolution models: a uniform comoving source emissivity, a standard-jet GRB population tracing the star formation rate (SFR), and a standard + narrow-jet GRB population tracing SFR. We propagate a mixed-composition UHECR injection and calculate the cosmogenic neutrino and cascade $γ$-ray fluxes. The standard + narrow jet model fits the observed UHECR spectrum and composition, with the highest-energy flux dominated by the narrow-jet population confined to $z\le z_{\max,*}\simeq0.36$. This low-redshift dominance lowers the cosmogenic neutrino flux compared to the standard-jet GRB population. For the narrow-jet GRB population, the fit implies a baryon loading factor $ξ_{\rm CR}^{\rm nj}\simeq10$. Such a locally enhanced long-GRB population can therefore explain the highest-energy UHECR flux without violating current multimessenger constraints. Future UHE searches can further probe this scenario through the associated cosmogenic fluxes.
Comments7 pages, 3 figures
