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Rei Nishiura's Homepage

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

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About Me

I am currently engaged in theoretical research in high energy astrophysics and plasma physics.

In particular, I am interested in understanding fundamental physical processes such as scattering and instabilities through analytical and numerical approaches, and applying them to astrophysical phenomena such as neutron stars, Fast Radio Bursts (FRBs), and Active Galactic Nuclei (AGNs).

Fields I have worked on (in the order I have focused on)

  1. Plasma physics(scattering, instabilities, kinetic theory)
  2. Electromagnetism(interaction between EM waves and charged particles)
  3. Magnetohydrodynamics(MHD, shocks, turbulence)
  4. Quantum mechanics(quantum mechanical approach to induced scattering)

Through teaching activities (e.g., as a teaching assistant), I have also worked on topics such as protoplanetary disks, gravitational waves, quasinormal modes, and Hawking radiation. More recently, through a collaborative project on Little Red Dots, I have also been working on the physics of stellar structure. In these contexts, I use Newtonian mechanics, special relativity, and general relativity as needed.

You can find my publications here:

Research

Fast Radio Bursts (FRBs)

Fast Radio Bursts (FRBs) are extremely bright radio pulses emitted over millisecond timescales. One of the most promising source candidates is a magnetar, which is an ultra strongly magnetized neutron star. The magnetosphere around a magnetar is filled with an electron and positron plasma, and when an intense electromagnetic wave such as an FRB propagates through it, nonlinear wave plasma interactions can amplify tiny fluctuations and trigger various instabilities. This physics is crucial for determining whether an FRB can escape or is attenuated during propagation.

I focus in particular on induced scattering (including induced Compton, Brillouin, and Raman processes), and I develop analytical theory applicable to ultra strong magnetic fields as well as validation through comparisons with kinetic numerical simulations.

First-author papers

  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

    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

    URL: APS

  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

    Status: Preprint (arXiv:2510.12869)

    URL: arXiv

Co-authored papers

  1. One-dimensional PIC Simulation of Induced Compton Scattering in Magnetized Electron-Positron Pair Plasma

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

    Status: Preprint (arXiv:2601.01169)

    URL: arXiv

Cosmic Ray Acceleration

Cosmic rays are high energy charged particles in the Universe, and one possible origin site is shocks driven by ultrafast outflows (UFOs) from Active Galactic Nuclei (AGNs). I investigate, using numerical simulations, how magnetic field amplification processes near shocks (e.g., the Bell instability) affect the acceleration efficiency and the maximum energy of cosmic rays.

First-author papers

  1. Bell Instability and Cosmic-Ray Acceleration in AGN Ultrafast Outflow Shocks

    Authors: Rei Nishiura, Tsuyoshi Inoue

    Status: Accepted to ApJ (arXiv:2510.13946)

    URL: arXiv

Little Red Dots

Recently, I have also participated in discussions of a collaborative project on Little Red Dots. While I am not leading this project, I contribute to the collaboration from a theoretical perspective.

Career

Employment

Fellowships

Activities

Teaching Assistant (TA)

Research Group Activities

Invited Talks and International Conference Presentations

Seminars and Presentations

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