超高能宇宙成因光子通量
Cosmogenic photon fluxes at ultra-high energies
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中文总结 AI 辅助
研究超高能宇宙射线产生的宇宙成因光子通量，通过考虑注入参数假设研究光子产率，量化不同源场景下的通量，发现不含初始质子的混合成分场景通量低于实验极限，有质子时相关通量可能可达，部分纯质子场景参数受光子极限约束。
中文摘要 AI 辅助
在超高能宇宙射线传播过程中会产生宇宙成因光子。其预期通量水平会因注入时宇宙射线的光谱、成分或源距离等参数而变化几个数量级。我们研究了注入参数的各种假设下的光子产率，发现对于能量高于\(10^{18}\) eV的宇宙成因光子，质子发射源在约15 Mpc距离处光子产率最大。虽然相同总能量下质子的光子产率总是超过重核的，但源距离增大时差异减小。接着，我们对不同源场景下的宇宙成因光子通量进行了量化。考虑了混合成分场景及纯质子或纯铁原初粒子的基准场景。不含初始质子的混合成分场景预测的宇宙成因光子通量比当前实验极限低超过1.5个数量级。若最高能量处有相当比例质子，相关光子通量可能可达。某些纯质子场景的参数组合已受当前光子极限约束。
英文摘要
During their propagation, ultra-high energy cosmic rays produce cosmogenic photons. The expected flux level of these photons may vary by orders of magnitude depending on parameters such as the spectrum and composition of cosmic rays at injection or the source distance. We investigate the photon yields for various assumptions on injection parameters. The photon yield is largest for proton-emitting sources at about 15 Mpc distance for cosmogenic photons above $10^{18}$ eV. While the photon yield from protons always exceeds the one from heavier nuclei of the same total energy, the differences are reduced for larger source distances. Then, we quantify the cosmogenic photon fluxes for different source scenarios. We regard mixed-composition scenarios that were found to provide a reasonable description of the data from the Pierre Auger Observatory. In addition, benchmark scenarios leading to comparably high ("maximum") or low ("minimum") photon fluxes are determined assuming pure proton or pure iron primaries. For the mixed-composition scenarios that do not contain initial protons, the predicted cosmogenic photon fluxes are below present experimental limits by more than 1.5 orders of magnitude. In case of a substantial fraction of protons at the highest energies, the related photon flux might be in reach. Certain parameter combinations of pure proton scenarios are constrained already by present photon limits.
