Probing the nature of gravity in the low-acceleration limit: wide binaries of extreme separations with perspective effects

Abstract

Recent statistical analyses of wide binaries have revealed a boost in gravitational acceleration with respect to the prediction by Newtonian gravity at low internal accelerations $\lesssim 10^{-9}$ m\,s${}^{-2}$. This phenomenon is important because it does not permit the dark matter interpretation, unlike galaxy rotation curves. We extend previous analyses by increasing the maximum sky-projected separation from 30 to 50 kilo astronomical units (kau). We show that the so-called ``perspective effects'' are not negligible at this extended separation and, thus, incorporate it in our analysis. With wide binaries selected with very stringent criteria, we find that the gravitational acceleration boost factor, ${\gamma }_g\equiv g_{\mathrm{obs}}/g_{\mathrm{N}}$, is $1.61_{-0.29}^{+0.37}$ (from ${\delta }_{\mathrm{obs}-\mathrm{newt}}\equiv ({\log }_{10}{\gamma }_g)/\sqrt{2}=0.147\pm 0.062$) at Newtonian accelerations $g_{\mathrm{N}}=10^{-11.0}$ m\,s${}^{-2}$, corresponding to separations of tens of kau for solar-mass binaries. At Newtonian accelerations $g_{\mathrm{N}}=10^{-10.3}$ m\,s${}^{-2}$, we find ${\gamma }_g=1.26_{-0.10}^{+0.12}$ (${\delta }_{\mathrm{obs}-\mathrm{newt}}=0.072\pm 0.027$). For all binaries with $g_{\mathrm{N}}\lesssim 10^{-10}$ m\,$s^{-2}$ from our sample, we find ${\gamma }_g=1.32_{-0.11}^{+0.12}$ (${\delta }_{\mathrm{obs}-\mathrm{newt}}=0.085\pm 0.027$). These results are consistent with the generic prediction of MOND-type modified gravity, although the current data are not sufficient to pin down the low-acceleration limiting behavior. Finally, we emphasize that the observed deviation from Newtonian gravity cannot be explained by the perspective effects or any separation-dependent eccentricity variation which we have taken into account.

15 pages, 12 figures

References in corpus (10)

• Gaia Data Release 3: Summary of the content and survey properties
• A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties
• The Local Dark Matter Density
• Proxima's orbit around Alpha Centauri
• From galactic bars to the Hubble tension: weighing up the astrophysical evidence for Milgromian gravity
• Breakdown of the Newton-Einstein Standard Gravity at Low Acceleration in Internal Dynamics of Wide Binary Stars
• Internal kinematics of GAIA DR3 wide binaries: anomalous behaviour in the low acceleration regime
• Numerical Solutions of the External Field Effect on the Radial Acceleration in Disk Galaxies
• A new scale in the quasi-static limit of Aether Scalar Tensor Theory
• Testing gravity with wide binaries -- 3D velocities and distances of wide binaries from Gaia and HARPS