A Quality Framework for Testing Gravity with Wide Binaries: No Evidence for MOND

TL;DR

This study develops a rigorous framework for testing gravity using wide binaries and finds no evidence supporting MOND, instead confirming Newtonian gravity within the tested acceleration range.

Contribution

The paper introduces a comprehensive methodology for analyzing wide binary data to accurately test gravity theories, addressing common pitfalls and applying it to Gaia data.

Findings

No MOND-like velocity enhancement observed in the data.

Newtonian gravity is strongly favored over MOND in the tested regime.

Methodological improvements reduce apparent MOND signals in previous studies.

Abstract

Wide binaries (WBs) offer a unique opportunity to test gravity in the low-acceleration regime, where modifications such as Milgromian dynamics (MOND) predict measurable deviations from Newtonian gravity. We construct a rigorous framework for conducting the wide binary test (WBT), emphasizing high quality sample selection, filtering of poor astrometric solutions, contamination mitigation, and uncertainty propagation. We show that undetected close binaries, chance alignments, and improper treatment of projection effects can mimic MOND-like signals. We introduce a checklist of best practices to identify and avoid these pitfalls. Applying this framework to Gaia DR3 data, we compile a high-purity sample of WBs within 130 pc with projected separations of 1 - 30 kAU, spanning the transition between the Newtonian and MOND regimes. We find that the scaled relative velocity distribution of wide binaries does not exhibit the 20% enhancement expected from MOND and is consistent with Newtonian gravity across all separations. A meta-analysis of previous WBTs shows that apparent MOND signals diminish as methodological rigour improves. We conclude that when stringent quality controls are applied, there is no observational evidence for MOND-induced velocity boosts in wide binaries. Our results place strong empirical constraints on modified gravity theories operating between a0/10 and 200 a0, where a0 is the MOND acceleration scale. Across this range of internal accelerations, Newtonian gravity is up to 1500x more likely than MOND for our cleanest sample.