Davis, Shane, AS-Astronomy (ASTR), University of Virginia
Abstract
We present a comparison between the general-relativistic ray-tracing code Blacklight and Monte Carlo radiative transfer methods implemented in ATHENA++ for modeling radiation transport in tidal disruption events (TDEs). Accurate treatment of radiation processes in TDEs is important for connecting general relativistic magnetohydrodynamic (GRMHD) simulations to future observable spectra. Blacklight computes observables by integrating along null geodesics and solving the radiative transfer equation along deterministic ray paths, which enables efficient post-processing of GRMHD simulations to create high-resolution imaging and spectra. In contrast, ATHENA++ Monte Carlo methods model photon propagation to statistically track photons as they propagate through a mesh, capturing scattering and emission processes that include Thomson and Compton scattering and free-free emission and absorption. Here, we evaluate the consistency of these differing approaches across three regimes: Thomson, Compton, and free-free scattering. We compare these approaches across Thomson, Compton, and free-free regimes to assess their consistency in predicted spectra and energy redistribution. We find an overall strong agreement between the two approaches across the tested radiative regimes. Both methods reproduce the expected thermal spectral behavior in free-free and scattering dominated environments across differing temperatures. The remaining discrepancies are primarily associated with Monte Carlo sampling limitations, frequency cutoff effects, and angular resolution sensitivity in the scattering source terms. These results demonstrate that Monte Carlo-derived scattering source functions can be successfully coupled to deterministic general-relativistic ray tracing and provide a promising framework for future radiative transfer studies of tidal disruption events.
Hudson, Nadara. Comparing ATHENA++ Monte Carlo Radiative Transfer and Blacklight General Relativistic Ray Tracing in Tidal Disruption Events. University of Virginia, Astronomy, BS (Bachelor of Science), 2026-05-12, https://doi.org/10.18130/74ek-jb59.
