Prospects for ray-tracing light intensity and polarization in models of accreting compact objects using a GPU

Abstract

The Event Horizon Telescope (EHT) has recently released high-resolution images of accretion flows onto two supermassive black holes. Our physical understanding of these images depends on accuracy and precision of numerical models of plasma and radiation around compact objects. The goal of this work is to speed up radiative-transfer simulations used to create mock images of black holes for comparison with the EHT observations. A ray-tracing code for general relativistic and fully polarized radiative transfer through plasma in strong gravity is ported onto a graphics processing unit (GPU). We describe our GPU implementation and carry out speedup tests using models of optically thin advection-dominated accretion flow (ADAF) onto a black hole realised semi-analytically and in 3D general relativistic magnetohydrodynamics simulations, low and very high image pixel resolutions, and two different sets of CPU+GPUs. We show that a GPU with high double precision computing capability can significantly reduce the image production computational time, with a speedup factor of up to approximately 1200. The significant speedup facilitates, e.g., dynamic model fitting to the EHT data, including polarimetric data. The method extension may enable studies of emission from plasma with nonthermal particle distribution functions for which accurate approximate synchrotron emissivities are not available. The significant speedup reduces the carbon footprint of the generation of the EHT image libraries by at least an order of magnitude.

arXiv comment6 pages, 1 table, 2 figures, Accepted to ApJS, after editorial corrections

References in corpus (17)

• First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• Black Hole Shadows, Photon Rings, and Lensing Rings
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• Universal Interferometric Signatures of a Black Hole's Photon Ring
• Observational appearance of inefficient accretion flows and jets in 3D GRMHD simulations: Application to Sgr~A*
• Universal Polarimetric Signatures of the Black Hole Photon Ring
• GRay: a Massively Parallel GPU-Based Code for Ray Tracing in Relativistic Spacetimes
• Odyssey: A Public GPU-Based Code for General-Relativistic Radiative Transfer in Kerr Spacetime
• Synthetic gamma-ray lightcurves of Kerr black-hole magnetospheric activity from particle-in-cell simulations
• Self-lensing flares from black hole binaries I: general-relativistic ray tracing of black hole binaries
• Images of magnetospheric reconnection-powered radiation around supermassive black holes
• Black Hole Glimmer Signatures of Mass, Spin, and Inclination
• Polarimetric signatures of hot spots in black hole accretion flows
• Observing supermassive black holes in virtual reality
• Relative depolarization of the black hole photon ring in GRMHD models of Sgr A* and M87*
• The Role of Adaptive Ray Tracing in Analyzing Black Hole Structure

Cited by in corpus (3)

• $\text{Jipole}$: A Differentiable $\text{ipole}$-based Code for Radiative Transfer in Curved Spacetimes
• $\text{GPUmonty}$: A GPU-accelerated relativistic Monte Carlo radiative transfer code
• Sensitivities of Black Hole Images from GRMHD Simulations