Dr. Tomohiko Oka

Research Experience:

2025.07 – present: Postdoctoral Researcher (JSPS Overseas Research Fellowships), JMU Würzburg, Germany

2023.09 – 2024.03: Part-Time Lecture, Department of Physics, Konan University, Japan

2023.04 – 2025.07: Postdoctoral Researcher (JSPS Postdoctoral Fellowships), Ritsumeikan Univesity, Japan

Educations:

2020.04 - 2023.03 : Ph.D. in Physics, Kyoto University, Japan

2018.04 - 2020.03 : M.S. in Physics, Kyoto University, Japan

Resolving the origin of cosmic rays by gamma-ray observations

Many mysteries remain in the evolution of the universe and the formation of stars and galaxies, and cosmic rays (CRs) are expected to play an essential role in solving these mysteries. However, even though a century has passed since the discovery of CRs, their origin --- where and how they originate and are distributed --- is still unknown. Megaelectronvolts (MeV) gamma-rays provide the robust information to identify the origin of CRs. In particular, nuclear de-excitation lines (e.g., 1.6, 4.4, 6.1 MeV) emitted by the interaction of CRs with molecular clouds are the most reliable probe of CR protons. Their observations can pinpoint the location of CRs and measure the amount accurately.

With the aim of detecting nuclear de-excitation line emissions from CR sources, I am contributing to the development of next-generation MeV gamma-ray observation projects: COSI and SMILE. I am particularly interested in improving the sensitivity above 1 MeV of the instruments by optimizing the analysis methods and understanding the background phenomena. I also build observational prediction models using multi-wavelength data and simulations.

Projects: COSI, SMILE, CTA