Rei Nishiura's Homepage

Contact

Email: nishiura[at]tap.scphys.kyoto-u.ac.jp

News

• October 2026: I gave a seminar at the High Energy Astrophysics Laboratory at Waseda University. I was again asked about the treatment of poles in the integral defining the plasma dispersion function, but could not answer on the spot. I was also fascinated by the depth of the group members’ research into microphysics. We also had a lively discussion about numerical methods that reduce computational costs by reformulating elliptic equations as a hyperbolic system.
• October 2026: I gave a seminar at the Space and Earth Science Group on the Komaba Campus of the University of Tokyo. A student raised an insightful question about contour integration for the plasma dispersion function, which I could not answer on the spot. Thank you for the lively discussion.
• August 2026: I spent a week visiting the Astronomical Institute at Tohoku University and participated in several group activities. I was also encouraged to gain research experience abroad.
• July 2026: I completed the fifteenth and final class of Science of Time and Space, which I taught as a part-time lecturer at Ryukoku University. As this was my first experience teaching a full course, designing the overall course structure was challenging.
• May 2026: I received the Student Presentation Award of the Physical Society of Japan at the 2026 Spring Meeting for my presentation Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres.
• August 2025: At the Faculty of Science “Research Experience Program 2025 in the Theoretical Astrophysics Group,” I gave an outreach talk aimed primarily at undergraduate students, explaining my research using, as far as possible, only high-school physics: Physics of Neutron Stars and Fast Radio Bursts .

About Me

You can find my publications here:

• arXiv
• NASA ADS
• INSPIRE

Research

Fast Radio Bursts (FRBs)

Fast radio bursts (FRBs) are extremely bright radio pulses observed over millisecond timescales. A leading source candidate is a magnetar, a neutron star with an exceptionally strong magnetic field. Its magnetosphere contains $e^\pm$ plasma. When an intense electromagnetic wave such as an FRB propagates through this plasma, nonlinear interactions between the wave and the plasma can amplify small fluctuations. These processes affect the scattering and attenuation of FRBs as they travel through the magnetosphere.

I focus in particular on induced scattering, including induced Compton, Brillouin, and Raman processes. I develop analytical theories applicable to extremely strong magnetic fields and test them through comparisons with numerical simulations.

More recently, I have extended this work to FRB generation through induced scattering. I am investigating whether a seed wave can undergo induced scattering in plasma and produce an intense scattered radio pulse observable as an FRB.

First-author papers

5. Fast Radio Bursts from Induced Upscattering. I. Magnetar Polar Fireballs

   Authors: Rei Nishiura, Kunihito Ioka, Bing Zhang

   Status: Preprint (arXiv:2609.36114)

   URL: arXiv

4. Induced scattering of fast radio bursts in magnetar magnetospheres

   Authors: Rei Nishiura, Shoma F. Kamijima, Kunihito Ioka

   Journal: Physical Review D 114, 063061 (2026)

   URL: APS / arXiv

3. Unified kinetic theory of induced scattering: Compton, Brillouin, and Raman processes in magnetized electron and positron pair plasma

   Authors: Rei Nishiura, Shoma F. Kamijima, Kunihito Ioka

   Journal: Physical Review D 113, 123070 (2026)

   URL: APS

2. Induced Compton scattering in magnetized electron and positron pair plasma

   Authors: Rei Nishiura, Shoma F. Kamijima, Masanori Iwamoto, Kunihito Ioka

   Journal: Physical Review D 111, 063055 (2025)

   URL: APS

1. Collective Thomson scattering in magnetized electron and positron pair plasma and the application to induced Compton scattering

   Authors: Rei Nishiura, Kunihito Ioka

   Journal: Physical Review D 109, 043048 (2024)

   URL: APS

Co-authored papers

1. One-dimensional particle-in-cell simulation of induced Compton scattering in a magnetized electron-positron pair plasma

   Authors: Shoma F. Kamijima, Rei Nishiura, Masanori Iwamoto, Kunihito Ioka

   Journal: Physical Review D 114, 063054 (2026)

   URL: APS / arXiv

Cosmic-Ray Acceleration

Cosmic rays are high-energy charged particles in the Universe. One possible acceleration site is a shock driven by an ultrafast outflow (UFO) from an active galactic nucleus (AGN). Using numerical simulations, I investigate how magnetic-field amplification near shocks, including the Bell instability, affects the acceleration efficiency and maximum energy of cosmic rays.

First-author papers

1. Bell Instability and Cosmic-Ray Acceleration in Active Galactic Nuclei Ultrafast Outflow Shocks

   Authors: Rei Nishiura, Tsuyoshi Inoue

   Journal: The Astrophysical Journal 997, 175 (2026)

   URL: IOPscience

Career

Education

• March 2021: B.S., Faculty of Science, Kyoto University
• March 2023: M.S., Graduate School of Science, Kyoto University
• March 2026: Completed the doctoral program, Graduate School of Science, Kyoto University

Employment

• April 2025–March 2026: JSPS Research Fellow (DC2)
• April 2026–present: JSPS Research Fellow (PD), Yukawa Institute for Theoretical Physics, Kyoto University
• April–September 2026: Part-time Lecturer, Ryukoku University

Activities

Teaching Assistant (TA)

• FY2022 (M2): Quantum Mechanics Exercise 2 (Kyoto University)
• FY2023 (D1): Project Research P5 (Kyoto University)
  Supervised theory seminars and numerical simulations for undergraduate thesis projects on protoplanetary disks.
• FY2024 (D2): Electromagnetism Exercise 2 (Kyoto University)
• FY2024 (D2): Project Research P5 (Kyoto University)
  Supervised theory seminars and numerical simulations for undergraduate thesis projects on general relativity, quasinormal modes, and Hawking radiation.
• FY2025 (D3): Project Research P5 (Kyoto University)
  Same as above.

Research Group Activities

• FY2024 (D2): Chair of AP Seminar (Kyoto University)
• FY2024– (D2–): Chair of GRB Seminar (Link)

Conference and Seminar Presentations

A. International Conferences

4. July 2026: Fast Radio Burst 2026 – Oral Presentation
   Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres
   (Guiyang, China)
3. January–February 2026: YITP Long-term Workshop “Multi-Messenger Astrophysics in the Dynamic Universe” – Presentation
   Unified kinetic theory of induced scattering in magnetized electron and positron pair plasma
   (Yukawa Institute for Theoretical Physics, Kyoto University, Japan)
2. May 2025: FRB Taiwan 2025 Conference – Oral Presentation
   Induced Compton scattering in magnetized electron and positron pair plasma and application to Fast Radio Bursts
   (Tainan, Taiwan)
1. November 2024: Fast Radio Burst 2024 – Oral Presentation
   Induced Compton scattering of fast radio burst in magnetized electron and positron pair plasma
   (Phuket, Thailand)

B. Invited Talks

1. March 2025: ISEE Joint Workshop – Invited Talk
   Induced Compton scattering of fast radio bursts in electron–positron plasmas
   (Kyoto University, Uji Campus, Japan)

C. Seminars

5. October 2026: Seminar, High Energy Astrophysics Laboratory, Waseda University
4. October 2026: Seminar, Space and Earth Science Group, Komaba Campus, The University of Tokyo
3. February 2025: High Energy Astrophysics Colloquium
   Induced Compton scattering in magnetized electron and positron plasma
   (Institute for Cosmic Ray Research, The University of Tokyo)
2. December 2024: PSR Bi-Monthly Meeting
   Induced Compton scattering in magnetized electron and positron plasma
   (Online)
1. October 2024: Theoretical Astrophysics Seminar
   Induced Compton scattering of fast radio bursts in magnetar magnetospheres
   (Tohoku University)

D. Oral Presentations

18. Fast Radio Bursts from Induced Compton Upscattering in Magnetar Polar Fireballs, High Energy Astrophysics Workshop 2026, Koshiba Hall, Faculty of Science Building 1, Hongo Campus, The University of Tokyo, October 6, 2026.
17. Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres, 2026 Autumn Annual Meeting of the Astronomical Society of Japan, Okayama Campus, Okayama University of Science, September 9, 2026 (W45a).
16. Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres, 2026 Spring Meeting of the Physical Society of Japan, online, March 2026.
15. Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres, 38th Theoretical Astrophysics Symposium “Numerical Simulations and AI in Astrophysics,” University of Tsukuba, December 2025.
14. Theory of Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres, High Energy Astrophysics Workshop 2025, Osaka University, Toyonaka Campus, December 2025.
13. Unified Theory of Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres, 80th Annual Meeting of the Physical Society of Japan, Hiroshima University, Higashi-Hiroshima Campus, September 2025.
12. Unified Theory of Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres, 2025 Autumn Annual Meeting of the Astronomical Society of Japan, Kaikyo Messe Shimonoseki, September 2025.
11. Unified Theory of Induced Scattering of Fast Radio Bursts in Magnetar Magnetospheres, YITP Workshop “Exploring Extreme Transients: Frontiers in the Early Universe and Time-Domain Astronomy,” Maskawa Hall, Kyoto University, August 2025.
10. Cosmic-Ray Particle Acceleration in Ultrafast Outflows from Active Galactic Nuclei, High Energy Astrophysics Workshop 2024, Tohoku University, October 2024.
9. Parametric Decay Instability of Fast Radio Bursts in Magnetar Magnetospheres, 2024 Autumn Meeting of the Physical Society of Japan, September 2024.
8. Parametric Decay Instability of Fast Radio Bursts in Magnetar Magnetospheres, 2024 Autumn Annual Meeting of the Astronomical Society of Japan, September 2024.
7. Parametric Instability of Fast Radio Burst in Magnetar Magnetosphere, Keihan Astrophysics Meeting 2024 Fall, K206, Yukawa Institute for Theoretical Physics, Kyoto University, October 2, 2024.
6. Induced Compton Scattering of Fast Radio Bursts in Magnetized Electron–Positron Pair Plasma, Exploring Extreme Transients: Emerging Frontiers and Challenges, Yukawa Institute for Theoretical Physics, Kyoto University, August 2024.
5. Thomson Scattering in Magnetized Electron–Positron Pair Plasma and Its Application to Fast Radio Bursts, High Energy Astrophysics Workshop 2023, The University of Tokyo, November 2023.
4. Scattering of Fast Radio Bursts in Strongly Magnetized Electron-Positron Plasma, YITP Workshop: Cosmic Plasma Revisited, Kyoto University, October 2023.
3. Collective Scattering of Fast Radio Bursts in Magnetar Magnetospheres, 2023 Autumn Annual Meeting of the Astronomical Society of Japan, Nagoya University, September 2023.
2. Particle Scattering of Fast Radio Bursts in Magnetar Magnetospheres, 78th Annual Meeting of the Physical Society of Japan, Tohoku University, September 2023.
1. Scattering of Fast Radio Bursts in Magnetar Bursts, High Energy Astrophysics Workshop 2022, Hiroshima University, November 2022.

E. Posters

3. Scattering of Fast Radio Bursts in Strongly Magnetized Electron-Positron Plasma, The Creation of Multi-Messenger Astrophysics, Gero Onsen, December 2023.
2. Scattering of Fast Radio Bursts in Magnetar Bursts, 35th Theoretical Astrophysics Symposium, Corasse Fukushima, December 2022.
1. Kilonova Radiation Models for Black Hole–Neutron Star Binary Mergers, 51st Summer School on Astronomy and Astrophysics for Young Researchers, online, August 2021.

Conference Organization and Outreach

A. Conference and Workshop Organization

LOC: Local Organizing Committee

7. Keihan Astrophysics Meeting 2026 Fall, LOC, K206, Yukawa Institute for Theoretical Physics, Kyoto University, October 2026.
6. Multi-Messenger Astrophysics in the Dynamic Universe, LOC, Panasonic Auditorium, Yukawa Hall, Yukawa Institute for Theoretical Physics, Kyoto University, January–February 2026.
5. Keihan Astrophysics Meeting 2025 Fall, LOC, Panasonic Auditorium, Yukawa Hall, Yukawa Institute for Theoretical Physics, Kyoto University, October 2025.
4. Exploring Extreme Transients: Frontiers in the Early Universe and Time-Domain Astronomy, LOC, Maskawa Hall, Kyoto University, August 2025.
3. Keihan Astrophysics Meeting 2024 Fall, LOC, K206, Yukawa Institute for Theoretical Physics, Kyoto University, October 2024.
2. Exploring Extreme Transients: Emerging Frontiers and Challenges, LOC, K206 and K102, Yukawa Institute for Theoretical Physics, Kyoto University, August 2024.
1. Cosmic Plasma Revisited: New Landscape of High-Energy Astrophysical Bursts, LOC, K206 and K102, Yukawa Institute for Theoretical Physics, Kyoto University, October 2023.

B. Outreach

1. Physics of Neutron Stars and Fast Radio Bursts, Faculty of Science “Research Experience Program 2025 in the Theoretical Astrophysics Group,” August 2025.