Our group integrates general relativity, computational astrophysics, and multi‑wavelength observations to investigate black holes and neutron stars. Below are our four current thrusts.
Horizon‑Scale Imaging & Tests of Gravity
We reconstruct and interpret horizon‑scale images of supermassive black holes (M87*, Sgr A*) to probe strong‑field gravity and relativistic plasma dynamics. We advance ML algorithms for mm/sub‑mm VLBI (e.g., KRISP/PRIMO), quantify systematics, and connect image morphology/polarization to spacetime and accretion physics.
Selected Publications
- The Unexpected Lack of Asymmetry in the Horizon-scale Image of Sagittarius A*, 2025
- The Image of the M87 Black Hole Reconstructed with PRIMO, 2023
- Black Hole Images as Tests of General Relativity: Effects of Spacetime Geometry, 2023
- Black Hole Images as Tests of General Relativity: Effects of Plasma Physics, 2022
- First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric, 2022
- First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole, 2019
Space‑Based Interferometry & Future Missions
We evaluate targets, frequencies, and architectures for space‑based VLBI to resolve a large number of black‑hole shadows and jets. Our goal is to develop a mission concept capable of expanding precision tests of gravity and accretion physics and image binary black holes emitting gravitational waves.
Selected Publications
- Modeling Targets and Optimal Frequencies for Imaging the Shadows of Nearby Supermassive Black Holes, 2025
- Advancing Black Hole Imaging with Space-Based Interferometry, 2024
- Kernel Methods for Interferometric Imaging, 2024
- Masses of nearby Supermassive Black Holes with Very Long Baseline Interferometry, 2012
Neutron Star Structure & Dense Matter
Using X-ray spectra, pulse‑profile modeling, and multi‑messenger data, we infer masses, radii, and the dense‑matter equation of state. We develop statistical frameworks to uncover correlations and biases and to synthesize constraints from X‑ray timing, spectroscopy, and gravitational‑wave observations.
Selected Publications
- Annual Reviews in Astronomy & Astrophysics: Masses, Radii, and the Equation of State of Neutron Stars, 2016
- Uncovering Correlations and Biases in Parameter Inference from Neutron-Star Pulse Profile Modeling, 2025
- Realistic finite-temperature effects in neutron star merger simulations, 2021
- Tidal Deformability from GW170817 as a Direct Probe of the Neutron Star Radius, 2018
- The Dense Matter Equation of State from Neutron Star Radius and Mass Measurements, 2016
- On the Mass Distribution and Birth Masses of Neutron Stars, 2012
- Astrophysical measurement of the equation of state of neutron star matter, 2010
Accretion & Plasma Microphysics
We develop GRMHD, PIC, and hybrid kinetic–GRMHD frameworks and electron thermodynamics models to capture particle heating and acceleration, reconnection, and wave cascades in radiatively inefficient accretion flows. These results inform multi‑scale simulations and predict observables for current and future facilities.
Selected Publications
- Covariant Guiding Center Equations for Charged Particle Motions in General Relativistic Spacetimes, 2025
- The Origin of the Slow-to-Alfven Wave Cascade Power Ratio and Its Implications for Particle Heating in Accretion Flows, 2024
- A New Covariant Formalism for Kinetic Plasma Simulations in Curved Spacetimes, 2023
- Global Electron Thermodynamics in Radiatively Inefficient Accretion Flows, 2023
- The Mechanism of Electron Injection and Acceleration in Transrelativistic Reconnection, 2019
- Electron and Proton Acceleration in Trans-relativistic Magnetic Reconnection: Dependence on Plasma Beta and Magnetization, 2018