Detailed numerical implementation of the wide binary test

Banik, Indranil; Charalambos, Pittordis,; Sutherland, William J.

doi:10.48550/arxiv.2109.03827

Cited by 3 publications

(2 citation statements)

References 25 publications

(50 reference statements)

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“…To advance our understanding of this phenomenon, it will be important to achieve more direct tests on the sub-pc scale. Three methods have been proposed to achieve headway: (i) Using very wide binary systems to test the law of gravitation (Hernandez et al 2012;Scarpa et al 2017;Banik et al 2021;Pittordis & Sutherland 2022, but see Clarke 2020Loeb 2022a).…”

Section: Discussionmentioning

confidence: 99%

Asymmetrical tidal tails of open star clusters: stars crossing their cluster’s práh† challenge Newtonian gravitation

Kroupa

Jeřabková

Thies

et al. 2022

Monthly Notices of the Royal Astronomical Society

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After their birth a significant fraction of all stars pass through the tidal threshold (práh) of their cluster of origin into the classical tidal tails. The asymmetry between the number of stars in the leading and trailing tails tests gravitational theory. All five open clusters with tail data (Hyades, Praesepe, Coma Berenices, COIN-Gaia 13, NGC 752) have visibly more stars within $d_{\rm cl}\approx 50\,{\rm pc}$ of their centre in their leading than their trailing tail. Using the Jerabkova-compact-convergent-point (CCP) method, the extended tails have been mapped out for four nearby 600–2000 Myr old open clusters to $d_{\rm cl} > 50\,{\rm pc}$. These are on near-circular Galactocentric orbits, a formula for estimating the orbital eccentricity of an open cluster being derived. Applying the Phantom of Ramses code to this problem in Newtonian gravitation the tails are near-symmetrical. In Milgromian dynamics (MOND), the asymmetry reaches the observed values for 50 < dcl/pc < 200 being maximal near peri-galacticon, and can slightly invert near apo-galacticon, and the Küpper epicyclic overdensities are asymmetrically spaced. Clusters on circular orbits develop orbital eccentricity due to the asymmetrical spill-out, therewith spinning up opposite to their orbital angular momentum. This positive dynamical feedback suggests Milgromian open clusters to demise rapidly as their orbital eccentricity keeps increasing. Future work is necessary to better delineate the tidal tails around open clusters of different ages and to develop a Milgromian direct n-body code.

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Section: Discussionmentioning

confidence: 99%

Asymmetrical tidal tails of open star clusters: stars crossing their cluster’s práh† challenge Newtonian gravitation

Kroupa

Jeřabková

Thies

et al. 2022

Monthly Notices of the Royal Astronomical Society

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“…It will therefore be important to jointly fit the wide binary and close binary populations, though it is probably safe to treat the two as independent and the close binaries as Newtonian. A careful statistical treatment is required to determine whether wide binaries can be fit using Newtonian gravity, or if they require a helping hand from Milgrom (for a detailed plan, see Banik, Pittordis & Sutherland 2021b). Properties of the close binary population can be deduced from the tail at high v and from systems with low r sky , where MOND effects should be insignificant.…”

Section: Using the Velocity Distributionmentioning

confidence: 99%

From galactic bars to the Hubble tension: weighing up the astrophysical evidence for Milgromian gravity

Banik,

Zhao

2021

Preprint

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Astronomical observations reveal a major deficiency in our understanding of physics − the detectable mass is insufficient to explain the observed motions in a huge variety of systems given our current understanding of gravity, Einstein's General theory of Relativity (GR). This missing gravity problem may indicate a breakdown of GR at low accelerations, as posited by Milgromian dynamics (MOND). We review the MOND theory and its consequences, including in a cosmological context where we advocate a hybrid approach involving light sterile neutrinos to address MOND's cluster-scale issues. We then test the novel predictions of MOND using evidence from galaxies, galaxy groups, galaxy clusters, and the large scale structure of the Universe. We also consider whether the standard cosmological paradigm (ΛCDM) can explain the observations, and review several previously published highly significant falsifications of it. Our overall assessment considers both the extent to which the data agree with each theory and how much flexibility each has when accommodating the data, with the gold standard being a clear a priori prediction not informed by the data in question. We also consider some future tests, including on scales much smaller than galaxies. Our conclusion is that MOND is favoured by a wealth of data across a huge range of astrophysical scales, ranging from the kpc scales of galactic bars to the Gpc scale of the local supervoid and the Hubble tension, which is alleviated in MOND through enhanced cosmic variance.

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A critical review of recent Gaia wide binary gravity tests

Hernandez,

Chae,

Aguayo-Ortiz

2024

Monthly Notices of the Royal Astronomical Society

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Over the last couple of years, the appearance of the third data release from the Gaia satellite has triggered various wide binary low acceleration gravity tests. Wide binaries with typical total masses ≈1.0 − 1.6M⊙ and separations above a few thousand au probe the low acceleration a ≲ a0 regime, where at galactic and larger scales gravitational anomalies typically attributed to the presence of an as yet undetected dark matter component appear, where a0 ≈ 1.2 × 10−10 m s−2 is the acceleration scale of MOND. Thus, studies of the relative velocities and separations on the plane of the sky, v2D and s2D respectively, of wide binary stars extending to separations above a few kau, provide an independent approach on the empirical study of gravity in the interesting a ≲ a0 acceleration range. Two independent groups, through complementary approaches, have obtained evidence for a departure from Newtonian predictions in the low acceleration regime, in consistency with MOND expectations for wide binary orbits in the Solar Neighbourhood. Two other groups however, have instead reported results showing a clear preference for Newtonian gravity over various MOND alternatives tested, over the same low acceleration regime. We here take a critical look at the various studies in question, from sample selection to statistical treatment of the wide binary relative velocities obtained. We discover a couple of critical problems in the formal design and statistical implementation shared by the two latter groups, and show explicitly how these yield biased conclusions.

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Detailed numerical implementation of the wide binary test

Cited by 3 publications

References 25 publications

Asymmetrical tidal tails of open star clusters: stars crossing their cluster’s práh† challenge Newtonian gravitation

Asymmetrical tidal tails of open star clusters: stars crossing their cluster’s práh† challenge Newtonian gravitation

From galactic bars to the Hubble tension: weighing up the astrophysical evidence for Milgromian gravity

A critical review of recent Gaia wide binary gravity tests

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