@inproceedings{10.1145/3815572.3815737,
author = {Bianco, Michele and Boschi, Tommaso and Bignamini, Christopher and Simsek, Osman Seckin and Keller, Sebastian and Ciorba, Florina M. and Revaz, Yves and Refregier, Alexandre},
title = {Accelerate Radiative Transfer Simulations for the Cosmic Epoch of Reionisation},
year = {2026},
isbn = {9798400727344},
publisher = {Association for Computing Machinery},
address = {New York, NY, USA},
url = {https://doi.org/10.1145/3815572.3815737},
doi = {10.1145/3815572.3815737},
abstract = {The most time-consuming part of radiative transfer cosmological simulations for the Epoch of Reionisation is the ray-tracing algorithm. This involves computing the hydrogen column density along the path of the ionising photons. In this work, we present an updated version of pyC2Ray1, a massively parallel ray-tracing and chemistry library that supersedes C2Ray which has been extensively employed in reionisation simulations and often requires millions of CPU-core hours across several thousand computing nodes on high-performance computers to simulate large-scale volumes. pyC2Ray implements the Accelerated Short-characteristics Octahedral RAy-tracing (ASORA) algorithm, a novel ray-tracing method explicitly designed for multi-source ray-tracing on GPUs. The algorithm is written in C++/CUDA and wrapped in a Python interface that enables easy, customised code usage without compromising computational efficiency. We demonstrate that the ASORA updates introduced in this work lead to a speed-up factor of 800 compared to C2Ray on a multi-core CPU. It is an indication that ray-tracing algorithms for cosmological simulations strongly benefit from GPU-acceleration and specialised software design development to achieve computational efficiency and physical accuracy.},
booktitle = {Proceedings of the Platform for Advanced Scientific Computing Conference},
articleno = {1},
numpages = {10},
keywords = {astrophysics, cosmology, massively-parallel simulations, ray-tracing, GPU acceleration},
location = {Bern, Switzerland},
series = {PASC '26}
}