Research interests

  • How compact object systems influence the microphysical, energetic, and dynamical properties of their surroundings.
  • Understanding how radiation (photons and particles, e.g., neutrinos) is produced in strong-gravity environments and subsequently attenuated by intervening media, thereby providing key information about the compact object, the state of the accreting material, and the underlying theory of gravity.
  • Calculating covariant and physically-accurate models of this radiation using a combination of phenomenology, theoretical physics, and computational astrophysics.

What I do

  • I authored and maintain the general-relativistic radiation transport (GRRT) code, “BHOSS”, which solves the equations of covariant polarised radiation transport and fully incorporates the effects of both special relativity and general relativity (or any metric theory of gravity).
  • By interfacing BHOSS with general-relativistic magnetohydrodynamics (GRMHD) simulations, I calculate the multi-frequency polarised emissions from turbulent plasmas surrounding black holes.
  • These calculations enable constraints on black-hole mass and spin, accretion physics, and facilitate strong-field tests of gravity.

What I’m part of

8K movie of the observed black hole shadow image around the candidate supermassive black hole in our Galactic Centre (Sagittarius A*), as seen at a wavelength of 1.3 mm (or 230 GHz frequency), the standard Event Horizon Telescope (EHT) observing wavelength. Such long wavelengths are necessary to peer through most of the accretion disk material and resolve structure close to the event horizon. The observer is orbiting at fixed longitude, passing though the North and South poles of the black hole, before returning to its starting position and completing a full orbit at fixed latitude. Note the strong gravitational lensing (image warping) and Doppler aberrational effects (varying brightness asymmetry). Movie made with my BHOSS GRRT code and using a=0.9375 Kerr 3D simulation data from the GRMHD code BHAC.

Movie of the observed supermassive black hole shadow in Messier 87 (M87), as calculated in BHOSS and using magnetically arrested disk (MAD) a=0.9375 3D GRMHD data from BHAC. The observer inclination, flow orientation, jet position angle, 230 GHz compact flux density, and 43 GHz & 86 GHz jet widths all satisfy M87’s observational constraints. The bright ring in the centre is the result of gravitational lensing of photons which orbit the black hole. The dark central brightness depression is roughly coincident with the event horizon and the innermost clockwise-rotating material is predominantly counter-jet material. “Flickering” coincides with magnetic eruptions of plasma in the accretion disc, and tenuous wisps of material in the outer parts of each frame are visible when the magnetic field in the disc is closely aligned with the observer’s line of sight.