An Integral-Based Technique (IBT) to Accelerate the Monte-Carlo Radiative Transfer Computation for Supernovae

• Published in: arXiv.org 2024-09
• Main Authors: Chen, Xingzhuo, Wang, Lifan, Kasen, Daniel
• Format: Article
• Language: English
• Subjects: Algorithms; Computation; Ejecta; Monte Carlo simulation; Radiative transfer; Signal to noise ratio; Supernovae; Symmetry; Time dependence
• ISSN: 2331-8422

We present an integral-based technique (IBT) algorithm to accelerate supernova (SN) radiative transfer calculations. The algorithm utilizes ``integral packets'', which are calculated by the path integral of the Monte-Carlo energy packets, to synthesize the observed spectropolarimetric signal at a given viewing direction in a 3-D time-dependent radiative transfer program. Compared to the event-based technique (EBT) proposed by (Bulla et al. 2015), our algorithm significantly reduces the computation time and increases the Monte-Carlo signal-to-noise ratio. Using a 1-D spherical symmetric type Ia supernova (SN Ia) ejecta model DDC10 and its derived 3-D model, the IBT algorithm has successfully passed the verification of: (1) spherical symmetry; (2) mirror symmetry; (3) cross comparison on a 3-D SN model with direct-counting technique (DCT) and EBT. Notably, with our algorithm implemented in the 3-D Monte-Carlo radiative transfer code SEDONA, the computation time is faster than EBT by a factor of \(10-30\), and the signal-to-noise (S/N) ratio is better by a factor of \(5-10\), with the same number of Monte-Carlo quanta.