My work involves developing and applying a physically motivated multi-zone jet model to a variety of low luminosity active galactic nuclei, fitting their radio to X-ray spectral energy distributions to constrain and better understand micro/macro jet physics and particle acceleration, and how it might vary between sources. Building on this, a new analysis pipeline is being developed that...
A key open question in astrophysics is how particles are heated and accelerated in accretion flows and how this shapes observed emission. We present a new method for reconstructing the connection between plasma dynamics and particle acceleration in the accretion flow of the LLAGN M87*, using the 2017 Event Horizon Telescope multi-wavelength campaign as a prototype. Our Bayesian framework...
The super-fast (~day), very-high-energy (VHE; >0.1 TeV) photon flares from the nearby active galactic nucleus M87 provide a unique, exciting opportunity to fast-forward our understanding of particle acceleration in jets. Despite 5 detected VHE flares in the last 20 years and extensive multiwavelength (MWL) campaigns, the process and location of these VHE flares in the jet are still not fully...
We investigate the composition and dynamics of black hole accretion jets using novel high-res GRMHD simulations. By deploying Lagrangian composition tracers and adaptive mesh refinement (AMR), we achieve two goals: 1) We precisely track how disk material mixes into the jet and how jet plasma entrains into the surrounding sheath, and 2) We maintain high resolution dynamically within the jet and...
I will review several energy extraction mechanisms (classical and quantum) to facilitate discussions on approaching the Blandford-Znajek process in the future.
The radio:X-ray plane is a valuable tool for probing the connection between core accretion and jet production in X-ray binaries during their hard spectral states. Although this correlation was once thought to be universal – and was extended to active galactic nuclei via a mass term – its universality is now questioned due to numerous ‘outliers’ that deviate from the ‘standard’ relation. To...
Binary systems with a stellar mass black hole accreting from a companion star show bright synchrotron flaring in radio through to the infrared, linked to changes in the accretion properties of the black hole and the launch of powerful transient large scale jets. Despite observations of flaring in ~50 X-ray binary systems over 50+ years, many questions remain about the nature of this behaviour....
X-ray binaries have recently emerged as a promising candidate to explain the highest energy cosmic rays. I will present an overview of the existing observational constrains provided by gamma ray telescopes, and introduce ongoing efforts to estimate the cosmic rays luminosity of these systems.
Jets from stellar mass black holes in X-ray binaries (XRBs) and supermassive black holes in active galactic nuclei (AGN) provide distinct opportunities to study the jets of black holes across two different mass regimes with very different selection effects. Historically, the apparent speeds of XRB jets have been observed to be lower than those of AGN, leading to the assumption that stellar...
The ALMA observatory is unprecedented in terms of high quality polarimetric observations at mm and sub-mm wavelengths. With its ~ 1 arcsecond resolution, ALMA can help us study the large scale (kpc) jets of AGN and possibly even untangle their magnetic field structure. I present brightness and polarization maps of M87 and characterize the key observational aspects of the jet, while at the same...
The images of the shadows of M87 and Sgr A*, taken by the Event Horizon Telescope using the technique of very long baseline interferometry (VLBI) at 230 GHz, have opened up a new window into horizon-scale black hole and accretion science. However, ground-based VLBI is hitting fundamental resolution limits due to the limited size of the Earth and atmospheric corruptions at high frequencies....
In this presentation I will explain how we use the open-source package "Resolve" to image VLBI data. Specifically we can use Resolve to dynamically image the sparse radio data observed by the EHT to image SMBH's like Sgr A and M87. I will introduce some changes that we have made to Resolve in order to improve the imaging of dynamical features and to open the path to multi-epoch reconstructions.
Accreting black holes span a wide range of regimes, from stellar-mass X-ray binaries to supermassive AGN, and they operate across very different accretion states. These systems are often modeled separately, and a key goal of our work is to test whether a single physical framework can describe these systems across both mass and accretion scales.
The fundamental plane of black hole activity—a...
General relativistic ray-tracing (GRRT) codes are used to track accretion disk photons back to the observer in order to create a simulated image. For polarized observations, such as those of M87*, the GRRT must also track the evolution of the full Stokes parameters. We have developed a new polarized GRRT code, Picasso, building on the previous unpolarized version. To validate the use of this...
This PhD research develops practical tools for millimetre astronomy, supporting blazar monitoring and evaluating the Africa Millimetre Telescope’s (AMT) role in global VLBI. A core component is a single-dish calibration and analysis pipeline for continuum blazar observations. Using IRAM 30-m test data, key calibration steps (pointing, opacity, elevation-dependent gain, and polarization) are...
The Event Horizon Telescope (EHT) has enabled horizon-scale imaging of supermassive black holes. However, constraining black hole spin remains a challenge, despite its importance for testing accretion physics, jet launching, and gravity. Therefore, it is worthwhile to investigate new methods for determining spin, particularly those that make minimal assumptions about the complex astrophysics...
Relativistic jets from black holes—spanning X-ray binaries to AGN—are natural laboratories for studying high-energy particle acceleration. Yet, how these systems convert bulk kinetic energy into nonthermal particle populations remains a central open question.
My work combines 3D RMHD simulations with polarized radiative transfer to model synchrotron and inverse Compton emission across the...
