A Synthetic–Real Universe Stress Test of the Radial Acceleration Relation: A Systematic Evaluation of Observational Bias versus Regime-Dependent Breakdown

This repository contains the complete, fully automated reproducibility package for the manuscript: "A Synthetic-Real Universe Stress Test of the Radial Acceleration Relation: A Systematic Evaluation of Observational Bias versus Regime-Dependent Breakdown". Abstract The Radial Acceleration Relation (RAR) serves as a hallmark empirical scaling law in galactic dynamics, exhibiting remarkable tight constraints in high-surface-brightness disk galaxies. However, low-acceleration systems and gas-rich dwarf galaxies consistently display systematic deviations and enhanced scatter, raising a critical question: does this breakdown reflect a true physical regime dependence or is it an artifact of observational and reduction-related biases? This study presents a rigorous statistical stress test to evaluate these competing hypotheses. We construct a synthetic universe where the RAR is exact by design ($R^2 = 1.000000$) and systematically inject severe observational perturbations, including random measurement noise, gas-mass uncertainties, gas-fraction correlated bias, inclination-related velocity noise, and distance errors. These controlled synthetic benchmarks are evaluated against uniformly processed real galactic data from the SPARC and LITTLE THINGS surveys. Our results show that the synthetic universal-RAR control is highly resilient; even under extreme noise injection (up to 150%), the relation remains strongly intact ($R^2 \simeq 0.63$) and fails to reproduce the catastrophic breakdown observed in real dwarf systems. In stark contrast, real low-acceleration SPARC subsamples degrade to $R^2 \simeq -0.34$, while the LITTLE THINGS dwarf sample exhibits a severe collapse to $R^2 \simeq -22.14$. A comprehensive suite of diagnostic tests—including galaxy-level bootstrap resampling, leave-one-galaxy-out cross-validation, and empirical corrections for pressure support/asymmetric drift and extreme inclinations—confirms that this breakdown is statistically robust and cannot be mitigated by standard observational corrections. Within the tested framework, commonly considered observational systematics are insufficient to mimic the observed dwarf-galaxy breakdown, strongly supporting the interpretation that the RAR undergoes a genuine, regime-dependent degradation in low-acceleration systems. Repository Structure & Reproducibility This package is built around a strict open-science reproducibility infrastructure. It includes all raw and harmonized data tables, processing scripts, statistical analysis routines, and visualization frameworks required to replicate every figure and numerical index reported in the manuscript../run.sh Included Components: Combined synthetic universe generation and perturbation routines. Unified data preparation pipelines for SPARC and LITTLE THINGS acceleration curves. Complete robustness testing suite (Galaxy-level bootstrap, leave-one-galaxy-out, threshold scans). Analytical and empirical correction models (pressure support, asymmetric drift, inclination MC tests). Automated high-resolution figure generation and manuscript compilation infrastructure.