Harmonic Angular Mapping Method for Binary Microlensing Grid Search
Abstract
Searching for binary-lens microlensing solutions is computationally demanding because of the complex parameter space and the large number of trial models required. We present an algorithm that accelerates binary-lens grid searches by expanding the angular dependence of precomputed magnification maps in Fourier modes. By contracting the observation-dependent weighted sums in Fourier space, the χ2 values for all trial source-trajectory angles can be evaluated efficiently using inverse fast Fourier transforms (FFTs), avoiding repeated calculations over individual observations. We tested the method on 200 Roman-like synthetic binary-lens events. For 166 events (83%), the recovered fits agreed with Levenberg--Marquardt fits initialized at the injected parameters to within |Δχ2|≤1. The FFT map scan required an average of 5.05~min per event. For the same discrete search volume, the Fourier angular evaluation was estimated to be approximately 900 times faster than conventional magnification-map sampling. These results demonstrate that the method can efficiently identify useful initial conditions for binary-lens light-curve modeling.
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BibTeX
@misc{nunota2026harmonic,
title = {{Harmonic Angular Mapping Method for Binary Microlensing Grid Search}},
author = {Kansuke Nunota},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.02326},
eprint = {2611.02326},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.02326},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Harmonic Angular Mapping Method for Binary Microlensing Grid Search
AU - Kansuke Nunota
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.02326
UR - https://arxiv.org/abs/2611.02326
AB - Searching for binary-lens microlensing solutions is computationally demanding because of the complex parameter space and the large number of trial models required. We present an algorithm that accelerates binary-lens grid searches by expanding the angular dependence of precomputed magnification maps in Fourier modes. By contracting the observation-dependent weighted sums in Fourier space, the χ^2 values for all trial source-trajectory angles can be evaluated efficiently using inverse fast Fourier transforms (FFTs), avoiding repeated calculations over individual observations. We tested the method on 200 Roman-like synthetic binary-lens events. For 166 events (83%), the recovered fits agreed with Levenberg--Marquardt fits initialized at the injected parameters to within |Δχ^2|≤1. The FFT map scan required an average of 5.05~min per event. For the same discrete search volume, the Fourier angular evaluation was estimated to be approximately 900 times faster than conventional magnification-map sampling. These results demonstrate that the method can efficiently identify useful initial conditions for binary-lens light-curve modeling.
ER -