Disk mass predictions for binary neutron star mergers: limitations of proposed symbolic regression models

Fuente: arXiv
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Main Author: Foucart, Francois
Format: Preprint
Published: 2025
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author Foucart, Francois
author_facet Foucart, Francois
contents Modeling disk formation and mass ejection in binary neutron star systems is an important component in the construction of models for the electromagnetic signals powered by these events. Most models rely on analytical formulae for the disk mass and dynamical ejecta that are fitted to the results of numerical simulations, yet these fits have large uncertainties that significantly limit our ability to extract information from merger observations. In a recent manuscript, Darc et al claim that disk mass formulae constructed using symbolic regression outperform existing formulae and robustly extend to regions of the parameter space outside of the fitting region. I show here that the improvement over the most directly comparable existing model comes mostly from the use of different error measures in optimizing the fitting parameters. For the limited training data used so far, that existing fitting formula has a performance similar to symbolic regression models when optimized over the same error measure. More importantly, I show that many of the formulae obtained through symbolic regression provide unphysical results when used over the whole range of parameters relevant to the modeling of binary neutron star mergers, making them dangerous to use within parameter estimation pipelines. I conclude that fitting formulae with more physics input (e.g. Lund et al 2025), albeit certainly imperfect, remain safer to use in data analysis than these symbolic regression results. Symbolic regression results used in conjunction with careful physics-based vetting may however outperform them in the future.
format Preprint
id arxiv_https___arxiv_org_abs_2511_11887
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Disk mass predictions for binary neutron star mergers: limitations of proposed symbolic regression models
Foucart, Francois
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Modeling disk formation and mass ejection in binary neutron star systems is an important component in the construction of models for the electromagnetic signals powered by these events. Most models rely on analytical formulae for the disk mass and dynamical ejecta that are fitted to the results of numerical simulations, yet these fits have large uncertainties that significantly limit our ability to extract information from merger observations. In a recent manuscript, Darc et al claim that disk mass formulae constructed using symbolic regression outperform existing formulae and robustly extend to regions of the parameter space outside of the fitting region. I show here that the improvement over the most directly comparable existing model comes mostly from the use of different error measures in optimizing the fitting parameters. For the limited training data used so far, that existing fitting formula has a performance similar to symbolic regression models when optimized over the same error measure. More importantly, I show that many of the formulae obtained through symbolic regression provide unphysical results when used over the whole range of parameters relevant to the modeling of binary neutron star mergers, making them dangerous to use within parameter estimation pipelines. I conclude that fitting formulae with more physics input (e.g. Lund et al 2025), albeit certainly imperfect, remain safer to use in data analysis than these symbolic regression results. Symbolic regression results used in conjunction with careful physics-based vetting may however outperform them in the future.
title Disk mass predictions for binary neutron star mergers: limitations of proposed symbolic regression models
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2511.11887