Both the lack of observation of ultra-high energy (UHE) photons and the limitations of the state-of-the-art methodology being applied for their identification motivate studies on alternative approaches to the relevant simulations and the related observational strategies. One such new approach is proposed in this report and it concerns new observables allowing indirect identification of UHE photons through cosmic ray phenomena composed of many spatially correlated extensive air showers or primary cosmic rays observed at one time. The study is based on simulations of interactions of UHE photons with the magnetic field of the Sun using the PRESHOWER program with some essential modifications. One of the expected results of such interactions is a generation of cosmic ray ensembles (CREs) in the form of very thin and very elongated cascades of secondary photons of energies spanning the whole cosmic ray energy spectrum. Upon entering the Earth’s atmosphere, these cascades or their parts may generate uniquely characteristic walls of spatially correlated extensive air showers, and the effect is expected also in cases when primary UHE photons are not directed towards the Earth. Particle distributions in these multi-primary UHE photon footprints are expected to have thicknesses of the order of meters and elongations reaching even hundreds of millions of kilometers, making them potentially observable with a global, multi-experiment approach, including re-exploring of the historical data, with the expected event rate exceeding the capabilities of even very large cosmic ray observatories. In this report, we introduce for the first time the methods allowing for simulating the isotropic flux of UHE photons in the Sun’s vicinity. Presented methods were verified and optimised in such a way that they would successfully model the cumulative spatial distribution of secondary photons at the top of the atmosphere. The preliminary results of simulations for the UHE photon flux of energy 100 EeV demonstrate the possibility of simulating potentially observable quantities related to CRE induced by UHE photons: densities, energy spectra and geographical orientations of secondary particles at the top of the Earth’s atmosphere. A measurement of at least one of these quantities would be equivalent to a confirmation of the existence of UHE photons, which would give an insight into fundamental physics processes at unprecedentedly high energies, far beyond the reach of man-made accelerators. On the other hand, a lack of such an observation would allow for further constraining of these fundamental processes with the physically new upper limits on UHE photon fluxes after careful analysis of the technical observation ability. The novel advantage of such an approach would lay in the purely electrodynamical character of the underlying simulations which are fully independent on extrapolations of hadronic interaction models by many orders of magnitude. Such extrapolations are necessary in the UHE photon identification methods based on the analyses of properties of individual extensive air showers presently used to determine the UHE photon upper limits.

中文翻译：

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太阳磁场中各向同性超高能光子通量的模拟

缺乏对超高能 (UHE) 光子的观察以及用于识别它们的最先进方法的局限性都激发了对相关模拟和相关观察策略的替代方法的研究。本报告提出了一种这样的新方法，它涉及允许通过宇宙射线现象间接识别 UHE 光子的新方法，该现象由许多空间相关的广泛空气簇射或一次观察到的初级宇宙射线组成。该研究基于使用 PRESHOWER 程序模拟 UHE 光子与太阳磁场的相互作用，并进行了一些必要的修改。这种相互作用的预期结果之一是产生宇宙射线系综 (CRE)，其形式为跨越整个宇宙射线能谱的非常薄且非常细长的能量次级光子级联。进入地球大气层后，这些级联或它们的部分可能会产生空间相关的大范围空气簇射的独特特征墙，并且在初级 UHE 光子不指向地球的情况下也会产生这种影响。这些多基元 UHE 光子足迹中的粒子分布预计将具有米量级的厚度和伸长率甚至数亿公里，这使得它们有可能通过全球、多实验方法观察到，包括重新探索历史数据，预期的事件发生率甚至超过了非常大的宇宙射线天文台的能力。在本报告中，我们首次介绍了允许模拟太阳附近 UHE 光子各向同性通量的方法。所提出的方法经过验证和优化，从而成功地模拟了大气层顶部次级光子的累积空间分布。UHE 光子能量通量 100 EeV 的模拟初步结果证明了模拟与 UHE 光子诱导的 CRE 相关的潜在可观测量的可能性：地球大气层顶部次级粒子的密度、能谱和地理方向。对这些量中的至少一个的测量将等同于确认 UHE 光子的存在，它将以前所未有的高能量深入了解基础物理过程，远远超出人造加速器的范围。另一方面，在对技术观察能力进行仔细分析后，如果缺乏这样的观察，将允许进一​​步限制这些基本过程，并使用 UHE 光子通量的物理新上限。这种方法的新优势在于基础模拟的纯电动力学特性，这些模拟完全独立于强子相互作用模型的外推多个数量级。这种外推在 UHE 光子识别方法中是必要的，该方法基于对目前用于确定 UHE 光子上限的单个广泛空气簇射的特性的分析。