RAPTOR I: Time-dependent radiative transfer in arbitrary spacetimes

Abstract

Observational efforts to image the immediate environment of a black hole at the scale of the event horizon benefit from the development of efficient imaging codes that are capable of producing synthetic data, which may be compared with observational data. We aim to present RAPTOR, a new public code that produces accurate images, animations, and spectra of relativistic plasmas in strong gravity by numerically integrating the equations of motion of light rays and performing time-dependent radiative transfer calculations along the rays. The code is compatible with any analytical or numerical spacetime. It is hardware-agnostic and may be compiled and run both on GPUs and CPUs. We describe the algorithms used in RAPTOR and test the code's performance. We have performed a detailed comparison of RAPTOR output with that of other radiative-transfer codes and demonstrate convergence of the results. We then applied RAPTOR to study accretion models of supermassive black holes, performing time-dependent radiative transfer through general relativistic magneto-hydrodynamical (GRMHD) simulations and investigating the expected observational differences between the so-called fast-light and slow-light paradigms. Using RAPTOR to produce synthetic images and light curves of a GRMHD model of an accreting black hole, we find that the relative difference between fast-light and slow-light light curves is less than 5%. Using two distinct radiative-transfer codes to process the same data, we find integrated flux densities with a relative difference less than 0.01%. For two-dimensional GRMHD models, such as those examined in this paper, the fast-light approximation suffices as long as errors of a few percent are acceptable. The convergence of the results of two different codes demonstrates that they are, at a minimum, consistent.

18 pages, 14 figures, 5 tables

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Cited by in corpus (43)

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• Fuzzball Shadows: Emergent Horizons from Microstructure
• Testing the Schwarzschild metric in a strong field region with the Event Horizon Telescope
• Generalized, energy-conserving numerical simulations of particles in general relativity. I. Time-like and null geodesics
• Jets, disc-winds and oscillations in general relativistic, magnetically driven flows around black hole
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• Self-lensing flares from black hole binaries I: general-relativistic ray tracing of black hole binaries
• RAPTOR II: Polarized radiative transfer in curved spacetime
• Generalized, energy-conserving numerical simulations of particles in general relativity. II. Test particles in electromagnetic fields and GRMHD
• GRMHD Simulations and Modeling for Jet Formation and Acceleration Region in AGNs
• Observing supermassive black holes in virtual reality
• Self-lensing flares from black hole binaries II: observing black hole shadows via light-curve tomography
• Deep Horizon; a machine learning network that recovers accreting black hole parameters
• Visibility of Black Hole Shadows in Low-luminosity AGN
• Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration
• Probing Quadratic Gravity with the Event Horizon Telescope
• The Role of Adaptive Ray Tracing in Analyzing Black Hole Structure
• The Variability of the Black-Hole Image in M87 at the Dynamical Time Scale
• Blacklight: A General-Relativistic Ray-Tracing and Analysis Tool
• The future ability to test theories of gravity with black-hole shadows
• Skylight: a new code for general-relativistic ray-tracing and radiative transfer in arbitrary spacetimes
• Bayesian Black Hole Photogrammetry
• Truncated accretion discs in black hole X-ray binaries: dynamics and variability signatures
• Illuminating Black Hole Shadow with Dark Matter Annihilation
• Forward Ray Tracing and Hot Spots in Kerr Spacetime
• Magnetic flux eruptions at the root of time-lags in low-luminosity AGN
• FANTASY: User-Friendly Symplectic Geodesic Integrator for Arbitrary Metrics with Automatic Differentiation
• Imaging the event horizon of M87* from space on different timescales
• A New Fast Monte Carlo Code for Solving Radiative Transfer Equations based on Neumann Solution
• Deep learning inference with the Event Horizon Telescope II. The Zingularity framework for Bayesian artificial neural networks
• Viscous torque in turbulent magnetized AGN accretion disks and its effects on EMRI's gravitational waves
• Synchrotron emitting Komissarov torus with magnetic polarization around Kerr black holes
• GALLIFRAY -- A geometric modeling and parameter estimation framework for black hole images using bayesian techniques
• A numerical study on the role of instabilities on multi-wavelength emission signatures of blazar jets
• Testing the Existence of Event Horizons against Rotating Reflecting Surfaces
• Synthetic gravitational lens image of the Sagittarius A${}^{\ast }$ black hole with a thin disk model
• $\text{Jipole}$: A Differentiable $\text{ipole}$-based Code for Radiative Transfer in Curved Spacetimes
• Sensitivities of Black Hole Images from GRMHD Simulations
• The Nature of Black Hole Shadows
• Construction of second-order six-dimensional Hamiltonian-conserving scheme