A new paper concludes that MOND effects are not present between wide binary stars (although not conclusively), and attributes the appearance that this is not the case the triple star systems that are mistaken for binary star systems.
This disfavors simple toy-model MOND, but favors approaches like that of Deur and of Moffat's MOG theory, which predict MOND-like effects in galaxies but do no not predict MOND-like effects in wide binary star systems.
We provide an updated test for modifications of gravity from a sample of wide-binary stars from GAIA DR3, and their sky-projected relative velocities.
Here we extend on our earlier 2023 study, using several updated selection cuts aimed at reducing contamination from triple systems with an undetected third star. We also use improved mass estimates from FLAMES, and we add refinements to previous modelling of the triple and other populations and the model-fitting. We fit histograms of observed vs Newtonian velocity differences to a flexible mixture of binary + triple populations with realistic eccentricity distributions, plus unbound flyby and random-chance populations.
We find as before that Newtonian models provide a significantly better fit than MOND, though improved understanding of the triple population is necessary to make this fully decisive.
Charalambos Pittordis, Will Sutherland, Paul Shepherd, "Wide Binaries from GAIA DR3: testing GR vs MOND with realistic triple modelling" arXiv:2504.07569 (April 10, 2025).
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Reference?
Found it: https://www.nature.com/articles/d41586-025-01090-3
You may recall that there were three schools of thought regarding the wide binaries. Chae reckoned the evidence was good enough to favor a specific type of MOND, Banik et al said it favored the null hypothesis of just GR, and Hernandez et al found mild evidence of non-Newtonian behavior. Stacy McGaugh considers Hernandez et al the best analysis so far...Two out of three authors on this paper come from Banik et al.
@Mitchell, which of the three, Chae Banik Hernandez do you think is most sound? I wish more independent research groups with the proper qualifications would weigh in on wide binaries and MOND vs Newtonian
McGaugh says Hernandez
@neo Keep in mind that the data set that all three of these groups are using for their wide binary data set is a pretty messy one because the sample is from the transition zone from Newtonian to MOND behavior, and not cleanly in the MOND regime, which means that you are looking a partial MOND effects and have to consider the interpolation function which isn't tightly pinned down by the data so far with several different possible interpolation functions, and there is some messiness to the data itself with the binary v. more than binary system contamination. Ultimately, we'd prefer to have a less analysis dependent sample of wide binaries fully in the MOND zone rather than the transition zone with systems that are more clearly established as having exactly two stars in the wide binary system ruling out more than two star system contamination. We'll probably get that some day. But we aren't there yet. It's hard to get conclusive results when you data set is so marginal.
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