Exploration of sources of ultra high-energy cosmic rays with GeV-TeV gamma-ray observations

超高能宇宙射线(UHECR)的来源尚不清楚。在加速地点，高能质子可以与周围的物质/光子相互作用，并发出特有的GeV-TeV伽马射线。最近，费米卫星或空气切伦科夫望远镜发现了新的伽马射线源。我开发了一个代码来模拟加速点的级联过程，并成功地将其改进为能够在本研究期间跟踪时间演变的代码。通过将我们的结果与观测结果相比较，我们研究了伽马射线源作为可能的加速地点。尤其是来自伽马射线暴(GRBs)的GeV伽马射线是很有前途的强子发射候选者。作为费米团队的一员，我为探索伽玛暴的发射机制做出了巨大贡献。不幸的是，目前可获得的伽马射线数据不足以从统计上揭示超高强度电离辐射的来源。但是，从基于我们开发的代码的结果中，我们发现了强子发射的特征光谱演化。这是一个重要的结果，可以用未来的观测来验证，如CTA，这将确定UHECRs的来源。

The sources of ultra high-energy cosmic rays (UHECRs) are unknown. In acceleration sites, high-energy protons can interact with ambient matters/photons, and emit characteristic GeV-TeV gamma-rays. Recently Fermi satellite or Air Cherenkov Telescopes have discovered new gamma-ray sources. I developed a code to simulate cascade processes in the acceleration sites, and succeeded in improving this to one that can follow temporal evolution in this research period. By comparing our results with observations, we have studied gamma-ray sources as possible acceleration sites. Especially, GeV gamma-rays from gamma-ray bursts (GRBs) are promising candidates of hadronic emissions. I have greatly contributed to exploration of the emission mechanism of GRBs as a member of the Fermi team. Unfortunately, the present available data of gamma-rays are not statistically enough to reveal the sources of UHECRs. But, from our results based on the code we have developed, we found characteristic spectral evolutions in hadronic emissions. This is an important result that can be verified with future observations such as CTA, which will determine the sources of UHECRs.