Research
High-energy astrophysics probes physics under conditions no laboratory on Earth can reproduce: the vicinity of black holes, relativistic jets, and explosive transients. Our group combines theory and simulations with multi-messenger observations across X-rays, gamma rays, radio, neutrinos, and gravitational waves. Our research is organized into two categories: Fundamental Astrophysics, which targets the extreme physics of the high-energy universe, and Applied High-Energy and Radiation Studies, which brings that expertise to practical challenges of the space age.
Numerical data from our papers are available on the Downloads page.
Fundamental Astrophysics
Anchored in two windows, black holes and MeV gamma rays, our work extends across a wide range of astrophysical phenomena, from the cosmic gamma-ray background and galaxy formation to star-forming galaxies and microquasars. Students in our group can work across the full arc, from building theoretical models to proposing observations and analyzing data.
Black Hole Astrophysics
Black holes are nature’s most extreme laboratories, where strong gravity, hot plasma, magnetic fields, and particle acceleration intertwine. Building on the first measurement of magnetic fields in the coronae of active galactic nuclei (Inoue & Doi 2018), we combine ALMA millimeter observations, IXPE X-ray polarimetry, and XRISM high-resolution spectroscopy to study coronae, accretion flows, and jets in the immediate vicinity of black holes.
Our scope extends well beyond AGN coronae: we study particle acceleration in the jets of microquasars such as SS 433, and the nHz gravitational-wave background produced by supermassive black hole binaries and its connection to galaxy formation. Particles accelerated in coronae and jets may reveal themselves as gamma rays and high-energy neutrinos, connecting our work directly to the sources of the neutrinos detected by IceCube. Through theory and observation together, we aim to establish black hole environments as multi-messenger laboratories.
High-Energy Astrophysics (MeV Gamma Rays)
The MeV band, between the X-ray and GeV gamma-ray windows, remains the last poorly explored frontier of observational astronomy, even though nuclear lines and direct signatures of particle acceleration lie in this range. We participate in the international GRAMS balloon experiment and contribute science studies and all-sky predictions for COSI and other next-generation MeV missions, helping to open up MeV astronomy.
Making full use of GeV observations with the Fermi satellite, we study the origin of the cosmic gamma-ray background, the populations of blazars and star-forming galaxies, particle acceleration in AGN coronae, and their connections to neutrinos and cosmic rays. It is a field where one can grow together with the missions themselves, from instrument concepts to science.
Applied High-Energy and Radiation Studies
The physics of energetic particles and radiation transport that we develop for astrophysics applies directly to real-world challenges of human activity in space. This category extends our fundamental toolkit into applied domains.
Lunar Radiation Environment
The Moon has no thick atmosphere or global magnetic field to shield its surface: galactic cosmic rays and solar energetic particles strike it directly, producing secondary neutrons and gamma rays in the lunar soil. Understanding this radiation environment, including both primaries and secondaries, is essential for the era of sustained human lunar activity that begins with the Artemis program.
Using the particle-transport and interaction physics honed in high-energy astrophysics, we work to understand and forecast the lunar radiation environment, quantifying how cosmic-ray variability and solar activity shape conditions on the surface, in support of the safety assessment of future lunar exploration.