pyC${}^2$Ray: A flexible and GPU-accelerated Radiative Transfer Framework for Simulating the Cosmic Epoch of Reionization

Abstract

Detailed modeling of the evolution of neutral hydrogen in the intergalactic medium during the Epoch of Reionization, $5\le z\le 20$, is critical in interpreting the cosmological signals from current and upcoming 21-cm experiments such as the Low-Frequency Array (LOFAR) and the Square Kilometre Array (SKA). Numerical radiative transfer codes provide the most physically accurate models of the reionization process. However, they are computationally expensive as they must encompass enormous cosmological volumes while accurately capturing astrophysical processes occurring at small scales ($\lesssim \mathrm{Mpc}$). Here, we present pyC${}^2$Ray, an updated version of the massively parallel ray-tracing and chemistry code, C${}^2$Ray, which has been extensively employed in reionization simulations. The most time-consuming part of the code is calculating the hydrogen column density along the path of the ionizing photons. Here, we present the Accelerated Short-characteristics Octahedral ray-tracing (ASORA) method, a ray-tracing algorithm specifically designed to run on graphical processing units (GPUs). We include a modern Python interface, allowing easy and customized use of the code without compromising computational efficiency. We test pyC${}^2$Ray on a series of standard ray-tracing tests and a complete cosmological simulation with volume size $(349\mathrm{Mpc}{)}^3$, mesh size of $250^3$ and approximately $10^6$ sources. Compared to the original code, pyC${}^2$Ray achieves the same results with negligible fractional differences, $\sim 10^{-5}$, and a speedup factor of two orders of magnitude. Benchmark analysis shows that ASORA takes a few nanoseconds per source per voxel and scales linearly for an increasing number of sources and voxels within the ray-tracing radii.

arXiv comment20 pages, 13 figures, 1 table

References in corpus (52)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• LOFAR: The LOw-Frequency ARray
• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• 21-cm cosmology
• Hydrogen Epoch of Reionization Array (HERA)
• Grackle: a Chemistry and Cooling Library for Astrophysics
• Reionization and the Cosmic Dawn with the Square Kilometre Array
• RAMSES-RT: Radiation hydrodynamics in the cosmological context
• Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\mathbf{z}\approx 9.1$ from LOFAR
• Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample
• The halo mass function through the cosmic ages
• Multi--dimensional Cosmological Radiative Transfer with a Variable Eddington Tensor Formalism
• The Phase II Murchison Widefield Array: Design Overview
• Deep multi-redshift limits on Epoch of Reionisation 21cm Power Spectra from Four Seasons of Murchison Widefield Array Observations
• C^2-Ray: A new method for photon-conserving transport of ionizing radiation
• Cosmological Radiative Transfer Codes Comparison Project I: The Static Density Field Tests
• Cosmic Dawn (CoDa): the First Radiation-Hydrodynamics Simulation of Reionization and Galaxy Formation in the Local Universe
• Simulating cosmic reionization: How large a volume is large enough?
• Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
• Cosmological Reionization Around the First Stars: Monte Carlo Radiative Transfer
• Radiation-magnetohydrodynamic simulations of HII regions and their associated PDRs in turbulent molecular clouds
• High Performance P3M N-body code: CUBEP3M
• A radiative transfer scheme for cosmological reionization based on a local Eddington tensor
• Most of the photons that reionized the Universe came from dwarf galaxies
• Cosmological Radiative Transfer Comparison Project II: The Radiation-Hydrodynamic Tests
• The Rise of the First Stars: Supersonic Streaming, Radiative Feedback, and 21-cm Cosmology
• AREPO-RT: Radiation hydrodynamics on a moving mesh
• TRAPHIC - Radiative Transfer for Smoothed Particle Hydrodynamics Simulations
• Reionization simulations powered by GPUs I: the structure of the Ultraviolet radiation field
• Hybrid Characteristics: 3D radiative transfer for parallel adaptive mesh refinement hydrodynamics
• A Multistep Algorithm for the Radiation Hydrodynamical Transport of Cosmological Ionization Fronts and Ionized Flows
• Lyman-alpha radiative transfer during the Epoch of Reionization: contribution to 21-cm signal fluctuations
• Bubble size statistics during reionization from 21-cm tomography
• SPHRAY: A Smoothed Particle Hydrodynamics Ray Tracer for Radiative Transfer
• The Large-Scale Observational Signatures of Low-Mass Galaxies During Reionization
• EMMA: an AMR cosmological simulation code with radiative transfer
• Simulating the Impact of X-ray Heating during the Cosmic Dawn
• Evaluating the QSO contribution to the 21-cm signal from the Cosmic Dawn
• Starbursts in low-mass haloes at Cosmic Dawn. I. The critical halo mass for star formation
• Neutral island statistics during reionization from 21-cm tomography
• Minimum size of 21-cm simulations
• Redshift-space distortions in simulations of the 21-cm signal from the cosmic dawn
• Quiescent low-mass galaxies observed by JWST in the Epoch of Reionization
• Radiative transfer of energetic photons: X-rays and helium ionization in C2-Ray
• Turbulence in simulated HII regions
• The Diffuse Nature of Stromgren Spheres
• The impact of inhomogeneous subgrid clumping on cosmic reionization II: modelling stochasticity
• Physics of Cosmic Reionization
• Suppressing variance in 21-cm signal simulations during reionization
• PhotoNs-GPU:A GPU accelerated cosmological simulation code

Cited by in corpus (5)

• Deep learning approach for identification of HII regions during reionization in 21-cm observations -- III. image recovery
• Impact of anisotropic photon emission from sources during the epoch of reionisation
• Mapping neutral islands during end stages of reionization with photometric intergalactic medium tomography
• CosmoUiT: A Vision Transformer-UNet Hybrid for Fast and Accurate Emulation of 21-cm Maps from the Epoch of Reionization
• Reionization in HESTIA: Studying reionization in the LG through zoom simulations